How to calculate the volume of a septic tank for a home: norms and common sense. Calculation of septic tank volume: formulas and examples Septic tank volume for 2 people

Suburban settlements are rarely provided with centralized collection and cleaning systems Wastewater... Few of today's residents live with "amenities" in the yard. An excellent way out of this situation is arrangement local sewerage system... To do this, you can use a ready-made container for a septic tank. By choosing this option, the work on the construction of the sewage system will be completed much faster than with the construction of tanks made of brickwork or reinforced concrete.

Types of containers

To date, it is quite easy to find a container for a septic tank on sale. There are various options: from ordinary plastic tanks installed as storage tanks to complex and multi-chamber stations equipped with pumps or compressors that are used for high-quality wastewater treatment.

What to choose depends on the consumer and on some factors:

• The nature and properties of the soil on the site. When choosing a container for a septic tank, you should take into account the characteristics of the soil and the levels of location groundwater... For example, the arrangement of filtration fields on clayey soils is irrational, such construction will take a lot of money and labor.
• The volume of drains in the house and the frequency of using the sewage system. If the house is used as a summer residence, that is, for living in it on weekends or holidays, then you can choose a simpler drive. When the structure is planned to be used continuously for permanent residence, then in such cases the housing is equipped with a full set of sewage equipment. In this case, it is worth purchasing a large container for a septic tank.

In modern construction, several methods are used to equip installations for local sewage systems:

• Septic tank- the simplest option. It is the safest analogue of a cesspool. Environmental friendliness is ensured by the tightness of such a container for a septic tank, it does not allow contaminated wastewater to enter the soil and violate the safety of the soil.
• Installation of local cleaning systems. This is a modern equipment in which a multistage purification of sewage streams is carried out. At the outlet of these systems, almost pure water is obtained, which can be discharged into reservoirs even without additional purification.
• Conventional septic tanks... Installing septic tanks that use mechanical or biological wastewater treatment is a good option. Such systems are supplemented with filter chambers or filtration fields.

This is one of the simplest arrangement options. local sewerage... All the outflowing water enters the septic tank. Cleaning of this tank is carried out by special machines (sewers). It should be borne in mind that the larger the volume, the less you will have to use sewers.

The volume of this type of septic tank is chosen, taking into account the estimated amount of drains. It is profitable to acquire container volume for a septic tank, which will be equal to the volume of the tank of the sewer truck.

Septic tanks not only collect wastewater, but also purify it in a certain way. This system includes a septic tank, which serves to settle the effluent. The incoming waste is distributed throughout the chamber, solid components fall to the bottom, light fractions rise upward, and partially purified water passes into the next compartment of the tank, in which further water purification is carried out by filtration or using bacteria. Further - the water is cleaned up in the soil itself.

Any owner of a country house wants to make their stay in it more convenient and comfortable. At the moment, modern construction of summer cottages and cottages mainly provides for the organization of autonomous water supply and sewerage.

Very often there is no provision for engineering communications outside the city. This mainly concerns the sewerage system. In view of this, those who became the proud owner of a country house begin to build autonomous sewerage system... In this case, it means the organization and installation of treatment facilities, which are called septic tanks. The construction of septic tanks can be performed using expanded clay concrete blocks, plastic containers, metal structures, reinforced concrete rings and everything else.

Often, septic tanks are a structure that consists of several chambers, which can be either concrete rings or finished devices... In some cases, the owners of a country house get by with simple digging of a hole and the construction of formwork around its entire perimeter.

A container for a septic tank, which would meet all the requirements for arranging sewage systems, can be made independently. To do this, you just need to weld a metal tank of the required volume. In such a container, it is necessary to provide for several sections, which will be separated by partitions for the primary purification of effluents. In the manufacture of a container for a septic tank with your own hands, there are a lot of options for creativity, your ideas may be limited only by the regulatory requirements developed for this type of containers.

When self-building a container for a septic tank, it must be borne in mind that such equipment will subsequently be placed underground. Because of this, such a structure must be strong enough and have special protective ribs that protect the septic tank from destruction during soil movements. This system must also be protected against corrosive processes.

The capacity for the septic tank must be supplied technological hatches for preventive maintenance during operation. You also need to provide it with holes for pumping fluids or for periodically cleaning the bottom from silting. For this, a cesspool can also be used, but such a decision can turn out to be quite bad consequences. An excess of groundwater can raise the level of the cesspool itself, and gases released during the decomposition of elements can enter the house through sewer pipes.

At the dacha, it is better to use septic tanks to create an autonomous system for treating wastewater and sewage waste.

Today there are a lot of companies producing containers for septic tanks.

They are made from:

• ferrous metals;
• of stainless steel;
• and different types polymers.

A wide range of different tanks are produced, which are manufactured in volumes from 300 liters to 10 thousand liters... Such containers are used in production for the collection and purification of process waters, as well as for their high-quality disposal. Properties various materials, which go to the production of these septic tanks, allow them to be used in different climatic conditions for the arrangement of autonomous sewage systems.

For the improvement of summer cottages or country houses you can buy a septic tank made in an industrial setting. The cost of such containers depends on many factors. Before you buy a container for a septic tank, you should carefully calculate the required volume. In this case, it is necessary to take into account the number of residents with a certain margin. The use of professionally made septic tanks in the sewerage systems of private houses or cottages can solve many problems. This option is the most acceptable in terms of time costs and is much more environmentally friendly than an ordinary one. cesspool.

When building septic tanks, it is necessary to comply with all standards for their location from residential buildings, as well as from wells or open reservoirs. When preparing a pit for this treatment complex, it is also necessary to take into account the depth of soil freezing and increase the size of the pit taking into account this parameter. A container for a septic tank made of plastic materials will serve excellently for many decades; it will be possible to add various additives to it to accelerate the processing of wastewater by microbes. This factor should also be taken into account when arranging a place for a treatment system.

In order for the septic tank to fully satisfy the needs of all people living in the house, it will be necessary to carry out the correct calculations of its required volume. Despite the fact that it must contain a sufficient amount of wastewater, it is desirable that it takes up as little space as possible and is compact.

You can give approximate calculations of the required volume of a septic tank, depending on the number of people living in a country house:

• up to three people - septic tank volume 1.3 cubic meters;
• from three to five people - 2.5 cubic meters;
• from six to ten people - 10 cubic meters.

These estimates are approximate and may vary due to certain factors.

One such factor will be. In this case, the amount of water consumed will decrease somewhat, since the owner of the house will try to save on its consumption. In view of this, it is safe to say that it will take a little to choose the volume of the septic tank.

If the house is inhabited by those who quite often take a shower, bath or use other plumbing fixtures, then the approximate figure of the required volume should be increased by one and a half times. As statistics show, the usual a person uses about 200 liters of water every day and to this figure must be added the same amount for various contingencies.

Septic tank calculation formula

In modern construction, where the installation of a two-chamber septic tank is required, there is a special formula according to which the required volume of the treatment plant is calculated:

B = (H * 0.2 + 0.2) * 2

B - the required volume of the septic tank, H - the number of residents in the house.

In addition, experts advise to be more far-sighted and take into account the possible increase in the number of people who will live in the house. Therefore, it is advisable to build a septic tank with a volume for a few more people, except for all family members who live in the house at the moment.

Undoubtedly, it is very important to correctly determine the volume of the septic tank, but do not forget about its shape. The main factor that affects the shape of the treatment plant is the level of soil freezing depth. Therefore, the depth of the septic tank should not exceed three meters.

Most owners of suburban buildings know that septic tanks used for collection and partial disposal household waste, can have a variety of designs. They can be mounted both from reinforced concrete rings of standard size and from plastic tanks. of various capacities... In this case, the most common option is considered to be a 2 or 3-section septic tank made of reinforced concrete rings. When choosing a septic tank configuration, special attention should be paid to the fact that the efficiency of such a treatment plant largely depends on its volume, therefore it is very important to correctly calculate a septic tank for a private house, regardless of the selected septic tank option and the shape of its constituent containers. When choosing this indicator, one should focus on the useful volume, which is calculated based on the triple water consumption per one person permanently residing in the house.

Taking into account the fact that the average statistical indicator of water consumption per person is about 200 liters per day, the total consumption is determined by multiplying it by the number of residents (see Appendix).

Application:

Number of people	Wastewater consumption, m 3 / day	Septic tank volume, m 3
3	0,6	1,5
4	0,8	1,9
5	1,0	2,4
6	1,2	2,9
7	1,4	3,4
8	1,6	3,9
9	1,8	4,4
10	2,0	4,8

Full calculation

The final or complete calculation of the septic tank, made in accordance with the current technical standards, presupposes a comprehensive account of the acting factors that manifest themselves in specific operational situations (in contrast to the approximate determination of its volume according to the table. Comprehensive accounting, as a rule, is subject to the following factors:

• deviation of the average water flow rate in one direction or the other;
• availability of free spaces for a septic tank of the required volume.

When considering the first of these factors, it should be noted that the above table is used only to roughly determine the volume of the reservoirs of the future treatment plant. Depending on the specific conditions, this value can deviate both towards higher and towards lower values. To account for such deviations, a special correction factor is introduced that corrects the average value by simple multiplication by it.

When using water metering devices, in particular, you will need to enter a correction for its consumable weight, which, accordingly, will reduce the volume of wastewater. In such situations, a so-called reduction factor of the order of 0.6–0.8 is introduced. For those who like to take a refreshing shower and bath every day, on the contrary, it will be necessary to introduce a multiplying factor of 1.5‒2. The presence of water-intensive household appliances (washing machine or dishwasher, for example) in a country house leads to the same result.

Taking into account the average daily water consumption by one user, as well as an additional correction for unforeseen costs (another 200 liters), the dimensions of the sedimentation tanks noticeably increase not only in volume, but also in the area occupied by the entire treatment plant. With a significant increase in water consumption (up to 5 m 3 per day), you will need to use a local treatment facility, consisting of two or three chambers, providing accelerated waste treatment.

Accounting for the occupied area

In the case of a limited plot of land allocated for the placement of a treatment plant, you, one way or another, will have to solve the issue of optimizing its linear dimensions (or rather, the usable area it occupies).

For this purpose, with a fixed volume, its linear dimensions can be varied in any way. So a concrete pipe with a diameter of 1 - 1.5 meters, dug into the ground vertically, can be used as a settling tank. The immersion depth of such a pipe in the ground can reach 2.5 m.

According to the shape of the sump used, its volume can be calculated using standard formulas.

For example, consider the calculation of the volume for a family of 4 people permanently residing in a suburban building:

1. Taking into account the average daily water consumption per person, as well as the data in the table in the appendix, a family of 4 people will need a sump with a total volume of at least 2 m 3.
2. To place such a reservoir, you will have to prepare a pit with an area of ​​2 m² and a depth of one meter.
3. In the event that you do not have the indicated area, it will be possible to allocate 1 m² of area under the sump, on which a two-meter-deep hole is dug.

With an increase in the required volume of the septic tank, the size of the prepared recess, respectively, increases.

Video

You can get more detailed information on the device, the operation of the septic tank and the calculation of its volume by watching the video below:

It is not at all easy to install an autonomous sewage system on your site, but it is necessary in the absence of a centralized urban system to ensure a comfortable stay.

An important component of the entire system is a septic tank, the task of which is to receive, purify sewage and release the purified liquid. At the same time, it is important to know exactly how to calculate the volume of a septic tank for a house, so that in the future there are no problems with overflowing the septic tank.

What the calculation consists of

The correct calculation of all parameters is necessary not only to obtain the exact volume of the future structure, but also to calculate the building materials, if it will be constructed by hand.

Internal chambers of a septic tank for a private house

Therefore, the following details are calculated:

• sizes of factory containers;
• daily volumes of wastewater that the device is able to receive and process;
• the amount of water used by people living in the house;
• building materials for the installation and construction of a septic tank.

Installation of both a factory and a home-made septic tank is carried out only after all the parameters and capabilities have been calculated.

Naturally, the material resources that are planned to be spent on its arrangement are also taken into account.

Very often, for those who only occasionally, on weekends, are in the country, it is sufficient to install a homemade device made of bricks, tires or concrete rings.

For year-round living in a house, it is best to purchase a factory version.

What else needs to be considered

Before digging a pit, you need to know the exact dimensions of not just the structure itself, but also all pipes, compressors and necks that occupy separate places.

taking into account the structure of the septic tank and the volume of each of its chambers

The installation of a septic tank should be carried out strictly in accordance with SNiP numbered 2.04.03-85, which indicates the exact distances of the alleged device from other objects. So:

• the distance to the house should be at least five meters;
• to a drinking well on loamy and clayey soils - from twenty five to thirty meters, and on sandy and cereal - from forty five to fifty;
• to garden trees - from five meters;
• to the neighboring site - from two meters;
• to the access road - from three to four meters;
• to the public road - from five to ten meters.

All these standards are taken into account at the design stage. To help, engineers and designers compile calculation tables, according to which it is easier to navigate if the site has few square meters, but the device is still required.

In addition, the depth of the structure is also calculated. It must be more than 130 centimeters, and the width and length must be more than one meter. The specified parameters are most suitable for one or two people.

The depth has its maximum. It is advisable not to make the depth of the septic tank more than three meters if it is supposed to be cleaned with a sewage machine.

Volume formula and number of people

For an accurate calculation, there is a standard formula:

W = K * Q, where K - means the period of settling of waste water, and Q - flow rate per day.

For a simpler option, use the daily rate of one person - two hundred liters, multiply the number by three (this is the number of days spent on processing wastewater) and divide the resulting amount by a thousand.

However, this is only a preliminary result. The values ​​can change depending on the people who are added as tenants - temporarily or permanently.

the size of the storage type septic tank

The volume of the future structure directly depends on the number of people living in the house. There are special tables for this, which can also be used in calculations.

Manufacturers of sewage septic tanks proceed from the useful volume parameter, which has an average value per day - two hundred liters. According to this indicator, it remains only to multiply the average number by the number of people living in the house, and you get the number by which the septic tank is chosen.

DIY materials

For the construction of a personal septic tank, accurate calculations are also needed, according to which building materials are selected.

These include not only containers, but also materials for the manufacture and arrangement of the foundation for it, various solutions or sprinkling, and so on.

To calculate the consumption of cement, for example, SNiP is used under the number 82-02-95.

For a septic tank made of concrete, rings are usually used, most often three. They have a standard diameter of one and a half meters and a height of ninety centimeters.

The resulting volume consists of the working and the so-called "dead", located above the level of the outlet pipe, from where the purified water goes into the ground or filtration fields.

In addition to rings, a cover plate and a cast iron hatch are used. Also important are materials for the construction of a ventilation system, the main part of which is asbestos cement pipe, at least one and a half meters long.

There are also tables for obtaining mixtures, where the exact ratios are given.

All materials for construction are approximately as follows:

• 3 concrete rings for one container;
• concrete ring with bottom;
• concrete ring with holes (for filtration wells);
• plate;
• ventilation pipe;
• cast iron hatch;
• cement, crushed stone, sand.

Of the tools that you need for installation, you can highlight:

• lifting crane;
• four to six people assemblers;
• concrete mixers;
• buckets;
• a wheelbarrow with a metal body;
• shovel;
• cutting tools.

Sewer pipes are brought to the septic tank and are firmly sealed.

If the septic tank serves, in addition to the sewerage inside the house, other drains, then appropriate consumables for them should also be provided.

selection of the size of the septic tank and its design

The cheapest homemade one will be the version of a septic tank made of tires. However, here, too, it is necessary to adhere to clear calculations for the arrangement.

The foundation and backfill is the same for all types of device.

For a container made of bricks, their approximate number is calculated, as well as bulk materials and other parts.

If it is planned to build a two-chamber structure, then the slab is made from a crushed stone pillow.

For counting bricks, there is a special table that tells you how much to use in square meters. In the resulting number, you need to lay about 5% for a brick break. Next, the masonry solution is calculated. It is best to use ready-made masonry mixes, which can be found in a large number of different types on the market.

Example for a family of four

To find out how to calculate the volume of a septic tank, you first need to get the three-day approximate water consumption of a family member. Then the time required to process the effluents is considered: 0.8xtx (100% -30% / 100%) * 120% = 0.8xtx0.7 × 1.2 = tx0.672 sec.

In this formula:

• 0.8 means the consumption of the remainder of large substances received from a person;
• t is the time of its decay per day;
• 100% - sludge volume;
• 30% - sludge decay;
• 120% / 100% - sludge volume and twenty percent of residues after cleaning carried out in the previous period.

You can take the minimum consumption per person - one hundred and fifty liters per day.

Then the average consumption will look like this:

• about ten liters of water takes off in a minute;
• shower lasts from seven to fifteen minutes;
• toilet use is approximately eight liters;
• one hundred and ten liters are consumed for a bath or jacuzzi;
• the washing machine consumes about seventy liters;
• the dishwasher consumes fifteen liters.

Thus, for one person it turns out: 110 + 8 * 5 + 10 * 7 + 150 = 370 liters per day. This is the highest consumption rate per day.

Both the minimum and maximum numbers are indicated in the corresponding SNiP. To calculate the total consumption (Q) of water, including the dishwasher and washing machine, you get:

• Q = 15 + 70 + 370 * 4 = 1.6 cubes.
• Remembering the formula Q * 3, for the whole family we get 1.6 * 3 = 4.8 cubes.
• This number is considered the best estimate.
• The minimum indicator is calculated as follows: 4.8 * (1-0.2) = 3.84 cubes.

The rate cannot be reduced by more than twenty percent, as in the indicated formula. If this rule is ignored, then the result can be flooding of the structure, which will lead to soil pollution.

overflow septic tank with drainage system and aeration system

An example of calculating the depth of a septic tank:

• 4.8 / 1 / 1.8 - 2.6 m;
• 4.8 is cubic meters in volume;
• 1 - m wide;
• 1.8 m in length.

This calculation is used for small plot sizes.

In some regions, the depth of soil freezing is up to two meters or more. It is necessary to strictly adhere to the norms and rules of SNiP, since otherwise the operation may be terminated and penalties may be imposed.

That is why, before installing a treatment plant, it is necessary to study all the rules and regulations, how to calculate a septic tank and strictly adhere to them.

Summer cottages and country houses have long ceased to be housing with amenities “in the yard”. New technologies and materials make it possible in a short time to build a full-fledged sewage system, which will provide drainage from the kitchen, toilet, bathroom or bath. Most often, it is not possible to connect the drain line to a centralized network, therefore, the problem of removing sewage from the site has to be solved independently, using the services of a sewer or dumping wastewater into the ground. Of course, in the latter case, you can build a simple drainage pit from scrap materials and thereby avoid financial costs, if not for one caveat: direct discharge of sewage into the ground can lead to groundwater pollution in your and neighboring areas.

In order for "both the wolves to be fed and the sheep to be safe," it is worth spending a small amount and building a septic tank that will clean the drains and make them safe. And so that the costs of its manufacture and operation do not lead to the depletion of the family budget, we recommend that you start building yourself.

Septic tank - a device, how it works

The issue of utilization of domestic wastewater in suburban areas can be solved in two ways. The first consists in the accumulation and subsequent removal of sewage using sewage machines, and the second covers a whole range of processes for their filtration, absorption and disinfection.

Using a sealed wastewater collection container is good option in the event that they appear in a country house or in the country on weekends and the amount of water used is small. If you plan to regularly operate the bathroom, toilet and household appliances, then the volume of water increases so much that you will have to pump out the drain pit weekly. To avoid this inconvenience, cesspools of a filtration type are constructed, in which the liquid from the sewage system is absorbed into the ground. There, with the help of bacteria, it is processed into water and safe organic matter... In fact, a septic tank is just such a structure, however, its improved design allows you to disinfect wastewater even before it is discharged into the ground.

Depending on the design, septic tanks can be divided into several types:

1. Single-chamber septic tank of small volume. It is a container with an overflow pipe and is used in small households with a water consumption of no more than 1 cubic meter. m per day. Despite the simple design, the efficiency of sewage treatment leaves much to be desired.


2. Small two-chamber septic tank. Consists of two containers connected by an overflow system. The simplicity and efficiency of such a design makes it the most popular for do-it-yourself manufacturing.
3. Multi-chamber structures. Due to the presence of several chambers, wastewater treatment takes place over a long period of time. This allows you to get water at the outlet, which can be safely discharged into natural reservoirs or used for household needs. Despite the high degree of purification, multi-chamber systems are few in number in private backyards due to their complexity and high cost.

In order to understand how a septic tank works, consider the most popular two-chamber design.

After the sewage gets from the sewer into the first chamber of the treatment plant, it is gravitationally separated into liquid and solids. At the same time, the processing of organic waste begins by aerobic and anaerobic bacteria, which develop in the absence or excess of oxygen. At the same time, not only liquid waste, but also fecal matter is processed into water and harmless organic matter. By the way, the work of microorganisms can significantly reduce the volume of the solid fraction, leaving only a small sediment in the form of sludge.

An overflow channel is located in the upper part of the first chamber, through which the purified liquid enters the second chamber, where it is further purified. Below the level of the inlet channel in the second tank there is an outlet branch pipe, from which the purified liquid is taken for watering the garden or diversion into the ground. In the latter case, they equip filtration fields or wells, which make it possible to increase the area of ​​contact of treated water with the ground.

Advantages and disadvantages of septic tanks

The question of which is better - a cesspool or septic tank, is best considered in terms of efficiency, as well as the cost of manufacturing and maintenance. It is important to remember about the safety of the structure.

Note that according to most parameters, it is the septic tank that wins, which stands out with such advantages:

• high degree of purification of domestic waste water - the water at the outlet of the device can be used for economic purposes;
• lack of an unpleasant odor on the site;
• hermetic design reduces the risk of sewage entering the groundwater and makes the structure safe for the environment;
• there is no need for regular pumping - the removal of sludge residue can be carried out once every several years.

The disadvantages of septic tanks include:

• more complex design;
• increase in construction costs;
• strict requirements for the use of household detergents. Conventional chemistry is detrimental to microorganisms, so you have to use special formulations;
• a decrease in the activity of bacteria with a decrease in temperature - at 4 ° C and below, the process of processing of sewage stops.

Despite some nuances, the use of a septic tank allows you to preserve the nature and health of others, and this is a plus that cannot be canceled out by any difficulties and financial costs.

Design and preparatory activities

The apparent simplicity of the design of the septic tank is very deceiving - in order for the constructed structure to be safe and productive, it is necessary to make small calculations and carefully approach the choice of location.

The choice of location on the site. Sanitary standards

When choosing a place for installing a septic tank, they are guided by the norms of sanitary and epidemiological legislation and acts of SNiP:

• local sewerage facilities are allowed to be installed at a distance of at least 5 m from the foundation of a residential building and 1 m from buildings for economic and domestic purposes located on the site;
• the distance from wells and boreholes is determined depending on the composition of the soil and can range from 20 m for clayey soils to 50 m for sandy soil;
• the installation of a septic tank directly near the roads and boundaries of the site is prohibited. It is required to maintain a distance of at least 1 m from the fence and 5 m from the road;

In addition, do not forget that from time to time you still have to use a sludge pump, so it is imperative to think about how the sewer truck will drive up to the sewage facilities.

You can do without the services of a sewer if the sludge is pumped out with a fecal pump purchased for this purpose, and the sludge from the septic tank is used as fertilizer for the garden.

Selection and calculation of material. Required volume

For the device of septic tank chambers, you can use both ready-made tanks and containers built by your own hands:

• bulky metal barrels;
• wells made of precast concrete structures;
• plastic eurocubes;
• monolithic concrete structures;
• brick wells.

The calculation of the amount of material required depends on the volume of the septic tank, therefore the main calculated value is the daily amount of discharged wastewater. It is not required to accurately determine this parameter; it is enough to take water consumption of 150-200 liters for each family member who permanently resides in the house. This will be enough for using the bathroom, toilet, washing machine and dishwasher. To determine the volume of the septic tank receiving chamber, the resulting value is multiplied by three. For example, if five people permanently live in a house equipped with all the amenities, then a tank designed for 3 cubic meters will be required. m of liquid waste (5 people × 200 liters × 3 = 3000 liters).

The second chamber is calculated based on the size of the receiving tank. If its volume is taken to be equal to 2/3 of the total size of the septic tank, then the dimensions of the post-treatment chamber provide the remaining third of the volume of the structure. If we take the example discussed above, then the working volume of the structure will be 4.5 cubic meters. m, of which 1.5 cubic meters. m is taken under the second tank.

Photo gallery: drawings of future structures

When designing a septic tank, you can use drawings and diagrams of working structures.

Calculations of external dimensions are carried out using well-known geometric formulas for determining the volume of a cylindrical structure and a rectangular container.

It should be understood that in most regions the septic tank will not freeze in winter due to warm drains coming from the house, soil temperature and the work of microorganisms. Nevertheless, you still have to deepen the structure. The gap between the cover and the upper level of wastewater is taken equal to the amount of soil freezing in winter. It is at this depth that the drain pipe enters the septic tank. Therefore, it is necessary to rely on the fact that the calculated working volume will be below this point. In addition, at a higher temperature, bacteria will more actively process sewage, contributing to an increase in the performance of the septic tank.

Which shape is better

The question of which septic tank is better - round or rectangular can be considered incorrect, since the shape does not at all affect the performance and degree of purification. However, the configuration of the structure makes a huge difference in the choice of materials. Everyone knows that round structures are the most optimal in terms of spending the necessary funds. The septic tank was no exception. If it is made of brick, then the choice of a cylindrical shape will reduce consumption by 10-15%. In addition, the round walls perfectly resist mechanical loads from the ground. If you choose a monolithic two-chamber structure, then it is better to make it square or rectangular. Firstly, the reinforced walls will withstand bending forces, and secondly, this is necessary for purely practical reasons associated with the manufacture of formwork for pouring concrete.

By the way, exactly concrete structure we recommend to do it yourself. If we consider the cost of a septic tank, then it will not be much higher than inexpensive brick counterparts (see table). As for the durability and strength of the structure, there can be no question of any comparison, therefore even more labor-intensive technology will justify itself many times over. How to build a rectangular two-chamber septic tank from reinforced concrete, we will tell you in detail.

Required tools and materials

To build a concrete treatment plant you will need:

• crushed stone, sand and cement for the manufacture of concrete;
• steel rods or fittings with a diameter of at least 10 mm;
• metal corners, pipes or channels for the construction of floors;
• boards, beams and slats for formwork;
• waterproofing film;
• concrete mixer;
• containers for bulk materials and concrete;
• Bulgarian;
• manual ramming;
• saw on wood;
• a welding machine or wire for the manufacture of an armored belt;
• hammer;
• building level;
• roulette.

If it is necessary to insulate a septic tank, this list should be supplemented with a heat insulator used, for example, expanded clay crumbs.

DIY construction and installation of a suburban septic tank made of monolithic concrete

1. After determining the size of the structure and choosing a place, they begin to dig a pit. The size of the pit is chosen depending on which formwork will be used. If boards made of boards are planned to be installed on both sides, then the pit is made 40-50 cm wider than the size of the tank, taking into account the thickness of its walls. In the case when concrete will be poured between the formwork and the ground, the pit is dug according to the outer dimensions of the septic tank. If hired people will be used for this, calculate the cost of their work. Be sure to keep in mind that the soil will have to be removed from the site, and this will entail additional costs for its loading. Perhaps the total cost of all earthworks will approach the cost of operating an excavator. At the same time, he will cope with the work dozens of times faster.
   

   It is not worth taking out all the soil from the site. Be sure to leave part of it for backfilling the septic tank.

2. Tamp the bottom of the hole and cover it with a layer of sand 10-15 cm thick. After that, the sand is spilled with water to compact it.
3. Install the formwork around the perimeter of the structure. If a one-sided board fence is used, then the walls of the pit are covered with plastic wrap. This will prevent them from shedding while pouring the walls and base of the septic tank.
4. Lay pieces of wooden slats at least 5 cm thick on the bottom. They will be needed as spacers for the reinforcement belt, which will be located inside the concrete base.


5. Build an armored belt from a metal bar or reinforcement. To do this, longitudinal elements are laid on the slats, and the transverse ones are attached to them by welding or tying with wire. The mesh size of the resulting lattice should be no more than 20 - 25 cm.
   

   A volumetric reinforcing frame is not required in the manufacture of a septic tank: a simple plane reinforcement is enough.

6. Pour the base of the septic tank with concrete and seal it with a bayonet or ram. The thickness of the bottom should be at least 15 cm. To prepare a mortar from grade 400 cement, you can use the following proportion: 1 part of cement is mixed with 2 parts of sand and 3 parts of crushed stone. When using M-500 cement, the amount of bulk materials is increased by 15 - 20%.
7. After the concrete base is finally set, they proceed to the construction of the formwork for the walls and partitions of the septic tank. Reinforcement is also installed inside the formwork to strengthen the structure of the structure.
   

   If there are not enough boards for the construction of the formwork to the full height, then a low sliding structure can be used, which is poured with concrete, and after it has set, it is moved up.

8. At the level of overflow channels and entry-exit points of sewer pipes, windows are made, installing pipe sections into the formwork large diameter or by constructing plank frames.
9. After the chambers of the septic tank have reached the required height, they begin to construct the floor. To do this, support elements made of steel corners or shaped pipes... In doing so, it is important to ensure sufficient strength, since concrete has a significant weight.
10. When installing formwork and reinforcement, take care of the openings for the hatches.
11. Fill the lid of the septic tank with concrete and cover the structure with plastic wrap.
12. After the overlap dries, a sewer main is brought into the receiving window of the first chamber, and the outlet of the structure is connected to drainage structures.
13. They fill the septic tank with soil, constantly tamping and leveling it. It is important that the ground level above the septic tank is slightly higher than the level of the entire site. This will prevent the wastewater treatment plant from flooding during heavy rains or floods.

Arrangement of filtration structures

In order to drain the treated water into the ground, drainage systems are used. of various types... The most common designs are filtration fields and drainage wells.

The first is a system of pipelines located in the ground and connected to the outlet of the septic tank. Thanks to the installation at an angle, the movement of treated wastewater through the pipes is ensured, and their absorption becomes possible thanks to the system of holes and the drainage layer into which the entire structure is placed.

The latter are a special case of a cesspool without a bottom and can be constructed from perforated concrete rings, staggered bricks, or old car tires. To ensure the absorption capacity, the bottom of the filtration well is covered with a thick layer of rubble. I must say that, unlike a cesspool, the performance of a structure connected to a septic tank practically does not decrease over time. This is due to the absence of solid particles and suspensions that can clog drainage holes and pores.

Using a septic tank, it is necessary to radically reconsider the approach to the use of sewerage. From the day the system is put into operation, it is forbidden to use chemical detergents and to pour any aggressive substances into the toilet or sink. It must be remembered that from now on, living things are engaged in wastewater treatment - bacteria and other microorganisms. Of course, this does not mean that you will now have to use ash and simple laundry soap for washing and cleaning, like our ancestors. When using household detergents marked "Bio" or "Eco", the fragile ecosystem of the septic tank will not be threatened, and you will receive good result when cleaning and washing.

You should not pour into the sewer and inorganic waste and garbage - there is a trash can for this. Getting into the storage tank of the sewage structure, they will collect at the bottom and interfere with its normal operation, and when pumping out sludge, they can clog the hoses fecal pump.

To improve the performance of the septic tank, special bioactivators are periodically added to the receiving chamber, which include several types of aerobic and anaerobic bacteria. When choosing biological products, it is imperative to pay attention to their purpose, since such compositions are produced both for normal conditions operation, and for cleaning heavily contaminated walls of septic tanks, drains with an increased fat content, etc. By the way, the compositions must be used exactly as indicated by the manufacturer on the packaging, otherwise bacteria may die.

From time to time you will have to check the sediment level. The fact is that their accumulation leads to a decrease in the useful volume and a decrease in the performance of the septic tank, therefore, from time to time, the sludge will need to be pumped out or removed using a sludge pump, fecal pump or a long pole with a scoop device. Of course, mechanized pumping methods will be preferable.

Video: homemade concrete structure for a private house

Despite the fact that the process of manufacturing a septic tank is associated with certain time and material costs, in the future, a treatment plant built with your own hands will justify itself more than once. You do not have to constantly think that the sewage system can "stand up" at the most inopportune moment or take care of the regular pumping out of the tank. The septic tank will be able to function long years without polluting environment and without causing any problems.

legkovmeste.ru

Types of septic tanks for a private house: plastic, concrete brick

Septic tanks are classified into several types. According to the materials of manufacture, containers can be:

• plastic - this is a ready-made septic tank for a private house;
• brick - these are the most inexpensive septic tanks;
• concrete - the most reliable and durable sewer wells.

Making a septic tank out of bricks is the most affordable way of arranging a drain pit. It does not require the work of loading equipment (as when working with heavy concrete rings) and costs the optimal sum of money... You can do it yourself; you do not need professional construction experience for the work.

A concrete septic tank is equipped with ready-made well rings. They are loaded into the pit using lifting equipment. Fittings are mounted between the rings as steps for lowering into the pit. This is the most reliable and durable arrangement of a sewer well. It requires money and the ability to access a loading and unloading crane.

To equip the sewage system quickly, they purchase ready-made plastic or metal containers. A plastic septic tank is cheaper than a metal one, and is also not subject to corrosion, is lighter and easier to install. Resistance of plastic to aggressive impact acids and alkalis, as well as the average price provided plastic septic tanks with popularity among other storage tanks

Classification of septic tanks according to the principle of operation

According to the principle of operation, septic tanks are classified into three groups:

• Accumulative - collect sewage and prevent it from entering the ground.
• Absorbing - collect wastewater, partially filter and dissolve in the ground, where the wastewater is finally cleaned.
• Bioseptics - completely purify waste water, give water at the outlet, which can be drained into an open reservoir.

Accumulative septic tanks

The accumulative design of the septic tank assumes that its capacity collects all the sewerage and stores it until it is pumped out by a sewer machine. Accumulative septic tanks are the most impractical types autonomous sewerage... First, they require frequent pumping, which means they are expensive. Secondly, accumulative septic tanks pose the question of strict water conservation before homeowners. Otherwise, you will have to pump out the contents of the pit every month.

Storage structures are justified if two separate septic tanks are being built (one for the toilet, the other for other drains). In such sewerage systems, a storage septic tank can be a container for collecting feces. All other drains, the volume of which is much larger, will be absorbed into the ground or soil after settling and filtration.

Absorbable septic tanks with soil purification

A septic tank with wastewater absorption into the ground is more profitable than a storage tank:

• Such a system does not require frequent monitoring of the work. At the right amount the sewer tank, the drains are absorbed into the soil through the bottom of the pit, without filling it to the top.
• There is no need to call a sewer truck to pump out the drains. So, less cost to work the sewerage system.
• The construction technology is simpler, since there is no need to make a septic tank completely sealed.
• It is cheaper to lay out the pit walls with a brick with your own hands than to purchase a plastic container for installation in the ground

The advantages of the design border on its disadvantages. We list the most important disadvantages of septic tanks with soil post-treatment:

• Contamination of groundwater and soil is possible. Therefore, such a sewage system should not be placed close to the coastline, in a water protection zone, where soil water flows close to the surface.
• For high-quality absorption of treated wastewater, it is necessary that the soil is sandy. In the clayey soil layers, runoffs are not absorbed, the septic tank becomes accumulative and requires periodic pumping.
• A pit with effluent resorption is located at least 5 m from residential buildings. Therefore, in small areas, there is often not enough space for the construction of such a sewage system.

Bioseptics

These are septic tanks with deep wastewater treatment. Sewage treatment uses mechanical filtration and sedimentation, biological treatment and chemical disinfection. The listed operations are performed in separate chambers.

A two-chamber septic tank without pumping works as follows: waste water accumulates in the first chamber. Here, the primary filtration and the release of heavy suspensions from the drains (they accumulate at the bottom) take place. After settling the effluents, the liquid enters the second chamber (by gravity), where it is purified by aerobic and anaerobic bacteria. An aerator (a device for saturating water with air) periodically operates here. It provides the conditions for aerobic bacteria to work. Heavy suspensions from the first cleaning chamber are disinfected with chemical reagents.

Bioseptic advantages:

• Wastewater treatment in bioseptics is so deep that after cleaning, water can be discharged into an open reservoir.
• A bioseptic can be built in any convenient place: next to the house or on the shore of a reservoir. The storage structure is equipped with drain pipes and an electric motor for periodically pumping out the purified water.
• The bioseptic is built on any soil. They are not absorbable sewerage systems, they do not require good soil porosity. Therefore, the storage tank can be installed both on sandy soils and in clays and loams.

Disadvantages of bioseptics:

• These are volatile devices. For their work, it is necessary to provide an electric current. That is not always possible and requires money.
• High price (up to 70,000 rubles for a septic tank + delivery price, ground works).

Septic tank device in a private house

In private houses, the most popular are septic tanks with filtration and drainage. How does a septic tank work in a private house if wastewater is purified in the ground?

The absorbable septic tank has the form of a cylinder without a bottom. The capacity of the septic tank is completely buried in the soil. The bottom of the septic tank is located below the freezing line. Deepening the septic tank into the ground for several meters ensures its non-freezing at any time of the year.

The water is drained into the tank near the surface of the earth. Sewer drains are transported to the pit through pipes that are buried in the ground above the freezing line. The slope of the pipes prevents water and faeces from stagnating and freezing even in severe frosts.

The bottom of the septic tank is covered with a layer of filter material (crushed stone, sand). When digging a septic tank, they try to go deeper into the sand layer. Sandy soil quickly absorbs water, this ensures timely removal of wastewater from the pit.

From above, the pit is closed with a concrete slab (floor slabs with a sewer hole) or a metal sheet. The tightness of the inner container controls penetration unpleasant odors outside, into the space of the yard next to the septic tank.

Diagram of a resorbable septic tank

The volume and dimensions of the septic tank

The volume of the septic tank depends on the number of people living in the house and the intensity of the use of plumbing devices. If there is a family of 2 adults in the house, while they use a shower and rarely take a bath, then the water consumption will be minimal, which means that the volume of the sewer tank will also be small (2-3 cubic meters). If lives in the house big family, while there are small children and connoisseurs of a daily bath, the water consumption will be increased, which means that the volume of the septic tank should be 6-8 cubic meters. How is the size of the sewer pit calculated?

Water consumption rates and septic tank volume

The calculation of the volume of a septic tank for a private house takes into account the number of people and the daily rate of water consumption. The norms of the 80s of the last century used an indicator of water consumption per person - 150 liters per day. The indicated 150 L was generated from the water consumption for cooking, washing dishes and flushing the toilet. If you add to it the water consumption for a daily bath and periodic washing, the consumption will increase to 250 liters per day (per person).

Official norms of monthly water consumption are 2.4 cubic meters per person (in an apartment) and 5.7 cubic meters per person (in a house with hot water supply). These norms are understated and are used to calculate preferential cubic meters, for which the state takes 50% of the payment. The simplest calculations show that the full use of water and modern household appliances requires more water consumption - up to 9 cubic meters. water per person monthly.

Septic tank effluent: absorption rate

The volume of the septic tank should take into account the daily water consumption and the rate of absorption of the effluent. If the soil is clayey, the effluent resorption will proceed slowly, the pit will be filled with sewage water and require pumping out. If the soil is sandy, the drains will be absorbed within several days.

If we assume that the absorption rate is 3 days, and the water consumption rate is 250 liters per person, then for a family (4 people) the required volume of the sewer tank is:

4 people * 250 l / day * 3 days = 3,000 liters or 3 cubes.

For a stock, a septic tank of a larger volume is purchased - 5-6 cubic meters per family (4 people).

Septic tank dimensions

The dimensions of the pit for installing a septic tank depend on the previously calculated volume and shape of the pit in the ground. For calculations, geometry formulas are used.

The volume of the cube is equal to the product of its edges or V = A * B * C, where A, B and C are the length, width and depth of the cesspool.

The volume of the cylinder is equal to the product of the area of ​​its base by the height or V = 3.14 * R2 * H, where R is the radius of the round bottom, H is the height of the cesspool.

If the volume of the septic tank should be equal to 6 cubic meters, then for a rectangular pit its dimensions can be 1 * 2 m - area and 3 m - depth. A cylindrical container or pit can have a diameter of 1.6 m and a depth of 3 m.

Installing a septic tank

The installation of a sewer tank begins with groundwork. In the place that is chosen for arranging the drain pit, soil is taken out. The dimensions of the pit should be 20-30 cm wider than the perimeter of the septic tank on each side.

The method of installing a septic tank depends on its type and material. How to install a concrete septic tank correctly?

Installation of concrete rings

The concrete rings for the sewer pit are installed using a crane. If the access of special equipment is difficult, then the rings are rolled to the place of the future drainage well and installed simultaneously with excavation. How this is done can be seen in the video. It shows the process of arranging a drinking well. The technique for installing concrete rings without a crane is the same for a drinking tank and a septic tank.

The ring is placed on the surface of the soil and a layer of soil is removed inside the ring and under its walls. So, layer by layer, the soil is removed and the hole deepened. In this case, the concrete ring falls down under its own weight. When the 1st ring is at the level of the soil, the 2nd ring is placed on top of it, and so on, all subsequent rings of the concrete well. After excavating the last layers of soil, the bottom of the pit is covered with rubble and sand. The total layer thickness of the filter media should be 30 cm.

Installing a plastic septic tank

Plastic has low strength characteristics. Therefore, plastic containers are not recommended to be installed directly into the ground. They are placed inside a pit with concrete (or brick) walls. The pit is concreted after excavation (reinforced with metal reinforcement and poured with concrete or bricked). This design increases the cost of the sewer system, but guarantees its durability and reliability.

A small septic tank is installed without a concrete "room". The space between the plastic wall and the pit is covered with sand. For this, a plastic container is placed in a pit and filled with water. If you pour sand without filling the septic tank with water, the plastic container will be squeezed up when filling.

Sand cover is a load absorber. In addition, it quickly removes water, so the material of the septic tank and the space next to it does not get wet and does not increase when freezing, which means it does not push the container upward from the ground.

The next element of safe installation of plastic "barrels" is concreting the bottom and fastening the septic tank to concrete. Such an "anchor" prevents the ejection of a light plastic container from the ground during winter freezing of the soil.

DIY brick sewer pit

The most affordable way to equip the sewage system on personal plot- this is to make a cesspool lined with brick. To do this, take out the soil, fold it a few meters nearby and proceed to the brickwork. Even a layman can lay out a cesspool with a brick. An ideal flat masonry plane is not required here. However, it is necessary that the brick wall is strong and does not collapse during the operation of the septic tank.

The brick is laid out at intervals, that is, in a row after 1-2 bricks, an empty space of 0.5 or 1 brick is left. Such rows alternate with rows of solid masonry. After 10-15 rows, metal reinforcement is placed between the opposite walls. It not only plays the role of steps for descending into the pit, but also serves as a thrust for opposite walls, increases the strength of the "leaky" brick structure.

Above, a well made of bricks is covered with boards and concreted. A small hole is left between the boards through which you can go down for a routine inspection. This hole is covered with a metal sheet and covered with earth. If necessary, look into the septic tank, rake the earth and raise the metal sheet.

Which septic tank to choose: compare materials and cost of work

The criteria for choosing a septic tank are based on the operating conditions of the sewage system and the total cost of work on the arrangement of the effluent outlet. The optimal choice combines the durability of the structure with the affordability of work and materials. The most inexpensive sewerage arrangement will cost you 1000 bricks and 2 bags of cement for mixing masonry mortar. The rest of the costs will be paid off by their own labor and personal time.

The most reliable and durable concrete septic tank will be assessed as the cost of 5-6 concrete rings and payment for their transportation and installation. To this it is necessary to add the cost of soil work - excavation of 6-10 cubic meters of soil (unless these works are done by hand).

The fastest sewer system is a plastic container, it is cheaper than concrete rings, but much more expensive than brickwork. The cost of plastic septic tanks depends on their volume and is 20,000 - 40,000 rubles. This also adds ground work, concreting the bottom and work on installing a septic tank in a pit. The total cost of arranging a sewage system with a plastic septic tank is calculated in the amount of 80,000 rubles.

The cost of an autonomous bioseptic is 60,000 - 70,000 rubles. (without installation and ground works).

The construction of a septic tank can be made for different purposes (drains from the toilet or all drains from the house), from various materials, with your own hands or by the work of professionals. The choice is yours.

ksportal.ru

The volume of septic tanks: a fundamental concept

Any septic tank has several chambers. And this means, in order to find out how many cubes in the septic tank, it is necessary to add up the volumes of all these departments. Also, it should be borne in mind that the calculations are based on the distance from the bottom to the level of the pipe. For example, if the volume of a two-chamber septic tank is calculated, then:

• for the 1st chamber, it is important to know the size of the gap between the bottom and the overflow pipe passing between the chambers;
• for the 2nd chamber, the distance between the bottom and the pipe for draining the treated water into the drainage well or filtration field is taken into account.

Important! In the first chamber of the septic tank, solid deposits will occupy about 20% of the entire height of the space. This factor must first of all be included in the calculation of a septic tank for a private house, at the stage of calculating the volume of only the liquid component of the effluent.

How to calculate a septic tank - regulatory framework

So, the volume of a septic tank for a summer residence (a house, a cottage, a mini-workshop) is a value directly proportional to the amount of waste generated. According to the current SNIP, at the rate for 1 person per day, 0.2 m3 or 200 liters is consumed. And when calculating, the volume is taken with a 3-day stock. This means that the minimum estimated volume of wastewater per person is 0.6 m3.

On the other hand, the same SNiPs indicate that it is possible to drain purified water into the landscape only after 14 days from the moment they enter the facility. It is during this period that the water will settle, and the anaerobic bacteria will do their part of breaking down organic inclusions.

Attention! The volume of a septic tank for a private house must be at least 2.8 m3. This figure is calculated by a simple mathematical operation: 0.2 m3 per day x 14 (the period of the waste water in the septic tank).

Required septic tank volume: practical experience

The norm of 200 liters of effluent per day per person in real life is rarely achieved - this is the maximum possible indicator. Team "New location" on Russian market the treatment plant has been operating practically from the moment of its formation. Based on our experience, it can be argued that the average daily volume of wastewater per person is about 0.1 m3, that is, 100 liters. Modern homeowners are very smart about resource use. They also use water sparingly. The data from practice is 2 times less than the normative ones. And in order to calculate a septic tank for a home, with optimal indicators, you can take an indicator of 150 liters per day per person as a guideline. So, to say with a focus on the intensive operation of household appliances, which are a source of wastewater formation. Naturally, the calculation of the septic tank is made for the number of residents. For example, for an average family of 4 people, a treatment system with a capacity of at least 6 cubic meters is needed.

When the savings are not justified

Discussing the situation, how much septic tank is needed in a particular area, we never recommend reducing the functionality of the facility "close to" real drains. In the construction industry, saving resources must be approached with extreme caution. This is due to the fact that even in household waste there are many inclusions that are difficult to process by anaerobic bacteria. And they cannot break down some substances at all. We mean, first of all, such complex compounds as fats.

Our task, as professionals, is to select the optimal volume of a septic tank for a private house, so that an effective clarification of wastewater takes place in the structure. Such a process involves the settling of suspended particles to the bottom. They are subsequently processed or pumped out using a sewage machine, and the treated water is discharged according to a scheme previously agreed with the client.

Important! The calculation of the volume of a septic tank for a private house should be oriented towards normal indicators upward. In this case, you can count on the structure to effectively cope with the assigned tasks, and there will be no problems with its maintenance. Otherwise, silt deposits and fats, after being diverted to a drainage well, will quickly clog the soil, and the water will no longer go further for filtration, that is, sewage treatment plant will fail. In short, you need to save "a little with a margin."

Calculation of septic tanks: how many chambers should there be

Above in the text, the emphasis has already been placed on the fact that the more chambers in a structure, the more efficiently it functions, providing a purification rate of up to 98-99%. This must be taken into account before calculating the volume of a septic tank for a home.

From the point of view of SNiP, the technical characteristics of treatment facilities can be updated as follows:

• A septic tank with one chamber is allowed with a waste volume of 1 cubic meter.
• At least two chambers are required for volumes up to 10 cubic meters.
• But over 10 m3, three-chamber septic tanks are shown.

Important accents

For waste water, the number of chambers that it has to overcome does not matter. The time spent in each of them is much more important. This parameter determines the calculation of a septic tank for the house. In this case, the number of cameras is not important, the main thing is the total volume of the object.

Organic inclusions of wastewater do not care how many sections are present inside the septic tank. If there is only one chamber, then suspended particles will settle unevenly and part of them will go further into a drainage well or filtration field. And to say that such a degree of purification is sufficient and water can be reused is not necessary at all. With two or more sections, the efficiency of the structure increases significantly.

We understand that it is quite difficult to calculate the volume of a septic tank for a consumer who has never faced such a task. Therefore, we recommend that you act in such a situation in the only rational way - contact the contact line of the Novoye mesto company. Already during the first consultation by telephone, our specialists will answer most of the questions that arise.

www.novoe-mesto.ru

It should be noted that the volume of a septic tank is the sum of the volumes of all its chambers. Also, the volume is considered from the bottom to the level of the pipe. For the first chamber - from the bottom to the overflow pipe between the chambers, and for the second chamber - to the drain pipe to a drainage well or to filtration fields.

It should also be borne in mind that in the first chamber the average height of solid deposits will be 20% of the chamber height. This volume must also be subtracted from the calculations if we are talking only about the liquid component.

Calculation of the volume of the septic tank.

The required volume of a septic tank is directly proportional to the amount of wastewater.

SNIP indicates that when calculating the volume of wastewater, the daily water consumption per person should be taken in an amount of 0.2 cubic meters. per day (200 l / day). And the volume should be calculated based on a 3-day supply. Then the minimum volume for one person is 0.6 cubic meters. For a family of 4 people - 2.4 cubic meters. Taking into account bottom sediments - 2.7 cubic meters.

For your information: sanitary standards indicate that the discharge of water from the septic tank into the soil (into the drainage well) should occur no earlier than 14 days from the moment it enters the septic tank. Those. settling water and purifying it with anaerobic bacteria in a septic tank should take at least two weeks.

Based on these statements, you will need a "giant" septic tank - for one person 2.8 cubic meters. (0.2x14). Accordingly, for a family of 4 people - 11.2 cubic meters. (4x2.8), which in general does not correspond to realities.

It should be noted that the waste flow rate specified in the SNIP of 200 l / person per day is not always achieved in practice. With the economical use of water, which is becoming typical for a private house, the volume of wastewater will be more likely 0.1 cubic meters. per day (100 liters) per person. Then the septic tank is "very economical" and does not meet the requirements of the standards (it can be rejected by the sanitary services), but nevertheless it works for 4 people, maybe 1.5 cubic meters. But this, again, for information, such septic tanks cannot be built.

Construction savings are not always beneficial. The effluent is full of substances that are difficult for anaerobic bacteria to process or not at all. First of all, these are heavy fats. It is important to make the treatment facilities in such a way that sufficient clarification of the water occurs in the septic tank. So that heavy substances and fat would settle to the bottom and be processed or later removed in the form of sediments by a sewage machine.

An increase in the volume of a septic tank will always have a positive effect on the quality of water purification and on its maintenance.

Therefore, an irresponsible decrease in the volume of a septic tank is not acceptable at all.

Number of cameras

When choosing the volume of the chamber and their number, it is also necessary to take into account the volume of the tank of a small sewage machine - 3.75 cubic meters. As well as the depth of the sludge pump - up to 3 meters. The working volume and depth of the first chamber should not exceed these values.

In principle, an increase in the number of chambers affects the quality of purification to a lesser extent than the entire volume of a septic tank. The important thing is the residence time of the drains - at least 3 days. As well as the composition of the water leaving the septic tank.
you can read more about How a septic tank should work normally

Therefore, to achieve the minimum volume of a septic tank for an "average" house of 2.7 cubic meters. it is also possible with a single-chamber septic tank (for example, such a volume is achieved by two reinforced concrete rings with a diameter of 1.5 m).

But if we recall the recommendations of sanitary standards, and the question of the preservation of the soil and the environment at home, as well as the fact that the drains are "difficult" especially when washing and washing equipment and an extra 1 - 2 days of sludge are necessary, then of course it is better to increase the volume, improve the quality of effluents, and of course apply a two-chamber septic tank, even for this case.

A single-chamber sewage treatment plant with filtration through the bottom (in fact, a cesspool), according to the standards, can be made only with a very insignificant flow, when the sewage system is used only occasionally in the country.

Which design option to choose

Consider the most common designs of septic tanks - made of reinforced concrete rings.

The standard ring height (most commonly used) is 0.9 meters.
The volume of one ring with an inner diameter of 1.0 meter will be 0.7 cubic meters. (0.5x0.5x3.14x0.7 = 0.7065).
With a diameter of 1.5 meters - 1.59 cubic meters.
With a diameter of 2.0 meters - 2.83 cubic meters.

The deepening of the drain pipeline at the entrance to the septic tank can be of different magnitude. It depends on the length and the specified slope. It is recommended not to bury yourself in the ground, it is more profitable to apply insulation. At the same time, do not carry the septic tank more than 10 meters from the house. But the slope to do at least 3% - insures against freezing and clogging.

Let's take an average pipeline deepening - 0.5 meters with insulation. Then the burial of the overflow pipeline from the first chamber to the second should be already 0.7 meters. The septic tank is insulated on top with extruded polystyrene foam with a thickness of at least 50 mm.

Thus, when using rings of 1.0 meters, 2 pieces per chamber, you can achieve a volume of a two-chamber septic tank of 2.7 cubic meters.

And the use in this case of 1.5 meter rings makes it possible to build single chamber septic tank the required volume (for our example).
But it is natural that a design with a margin of volume and number of chambers is objectively better, for example, the first chamber - 2 reinforced concrete 1.5 meter rings, the second - 2 rings but already with a diameter of 1 meter. Another question is how much money should be saved during construction….

More information about the construction of a septic tank can be found here

stroy-block.com.ua

Regulatory Requirements

The sewerage system of a private house consists of several key elements:

1. Dumping points for sewage and waste.
2. Drainage and sewerage pipe system in the building itself.
3. Pipes below the surface outside the building.
4. A septic tank, the volume of which is sufficient for the functioning of the system, as the end point of the "reception" of waste and their purification.

The most important steps before starting installation work:

1. Determination of the location of the elements of the sewerage system.
2. Preparing the plan.
3. Calculation of the size, volume and other parameters of the septic tank.
4. Preparation of materials.

Since all waste will be collected at the end point of the system, calculating the volume of a septic tank for a private house is a key preparatory step. Errors during this procedure will have disastrous consequences that will result in permanent failures in the system.

When working out the plan, it is important to take into account the sanitary requirements for the distance of the septic tank from the key facilities on the site. These requirements are set out in SNiP 2.04.03-85 “Sewerage. External networks and facilities ". The requirements of the standards can seriously affect the calculations, since everything is linked to the size of the land plot. If the area is small, and the number of people living is large enough, problems may arise with the work on the arrangement of an autonomous sewage system.

The key characteristics of remoteness, which must be familiarized with and taken into account when planning, include the following parameters:

1. Distance from the residential building.
2. Distance from a drinking well, well or other source of water of an artificial or natural nature, taking into account the carrying capacity of the soil.
3. Differentiation with plantings of vegetation.
4. Taking into account the distance from neighboring areas.
5. Distance from transport routes for access to the tank of the sewer truck, compliance with the requirements for distance to protect systems from vibration.

Dimensions and volume

Calculation of a septic tank involves determining:

• the size of the case of a factory or homemade container;
• the volume of the container;
• daily volumes of waste and sewage discharge;
• daily water consumption for each consumer living in a residential building;
• the amount of materials and funds (especially important for an independent septic tank device).

The key parameter of all calculations is the number of people planned to live in the house; permanent, seasonal or temporary residence.

The best option is to equip a special factory-made septic tank. But if you plan to install an autonomous sewage system in your country house, where you rarely visit or are limited in finances, the option with self-production a septic tank made of bricks, concrete rings or even tires.

According to SNiP, the size of the septic tank per resident: the depth should not be less than 130 cm, the width and length - not less than 100 cm, the depth from the surface to the bottom of the tank no more than 320 cm (subject to mandatory maintenance with special equipment for systematic cleaning).

It is worth distinguishing between the dimensional characteristics of the septic tank itself and the pit, which must fit the container, pipes, compressors and other elements of the system. Indicators of daily waste discharges and water consumption are necessary to determine the parameters of the tank itself.

With a factory septic tank, consisting of several chambers, everything is quite simple - all the necessary parameters and calculations are indicated in the technical documentation for the capacity. At limited space site, a large number of people living and independent equipment of a septic tank will require additional detailed calculations, taking into account all factors.

For these purposes, specially developed septic tanks calculation tables are used:

1. Table of liquid consumption by one consumer in 24 hours.
2. Table of average daily water consumption by one person.

According to the table, it turns out that for one person in a residential building it is necessary:

• 125-160 liters of cold water supply.
• 160-230 liters of water with a water heater.
• 230-350 liters of water with a centralized hot heating system.

Calculation of dimensions and volume

To accurately determine the internal space of the tank, a specially developed formula for calculating the volume of a septic tank is used. But it implies a large number of complex meanings and is difficult for private practical application. In practice, the volume of a septic tank for a private house is calculated using a simpler formula. Number of people X 200 liters of sewage rate per person X 3 days (waste processing time) / 1000 = volume in cubic meters. Most often there are 4 people in a family. Consider an option with the calculation of the volume for this number of family members. 4x200x3 / 1000 = 2.4 cubic meters m. A septic tank for 5 people will require a volume of 3 cubic meters. m. Calculated by this formula, the volume for 6 people is 3.6 cubic meters. m. For 20 people, the calculated figure is 12 cubic meters. m.

When calculating the parameter "number of people" it is better to take "with a margin" in order to take into account the load when visiting guests and other unforeseen situations. Daily rate can be increased if there are small children, pets. This indicator also increases if you use a large number of different household appliances with water consumption (washing machine).

As mentioned above, there are laboratory calculations that are given for factory septic tanks. According to this data, it is possible to carry out calculations in situations with containers made by yourself.

So, with a septic tank in three sections:

• for two people, a useful volume of 1.5 cubic meters is required. m .;
• for three or four people - 2 cub. m .;
• for five or six people - 3 cubic meters. m .;
• for eight people - 4 cubic meters. m .;
• for ten people - 5 cubic meters. m .;
• for twenty people - 10 cubic meters. m.

The main building material when arranging a septic tank, concrete rings are independently. And the key calculation is to determine the amount of these materials. Most often, 3 reinforced concrete rings with a diameter of 1.5 m and a height of 0.9 m are enough. More than 5 rings are not used per septic tank.

Do not forget about other elements when setting up the system yourself. These include:

1. Reinforced concrete plate.
2. Ventilation pipe.
3. Cement, sand, crushed stone.

When calculating the required volume of a septic tank, the formulas given above are used. In addition, it is necessary to know the volume of one ring in order to determine the sufficient number of rings in the container.

A ring is a conditional cylinder, and its volume is calculated using the corresponding formula.

V = ∏R2H = ∏ (d2 / 4) H, where:

• V is the volume of the cylinder;
• ∏ - number Pi (3.14);
• R is the radius of the base;
• d - base diameter;
• H is the height.

Knowing the volume of the ring, it can be compared with the obtained figures of the required volume concrete septic tank... The volume of 1 ring (d = 1.5 m; H = 0.9 m) is approximately 1.6 cubic meters. m. It turns out that for 4 family members in a house with all the amenities (hot water, etc.), you will need 2 rings to equip a septic tank.

This amount will be enough for 5 people. Up to 10 people can be provided with one container of 3 rings. If you plan to live from 10 to 20 people, you will need to equip a septic tank, consisting of several containers, since more than 3 rings cannot be installed. In this case, it is better to take care of purchasing a factory model of sufficient volume.

vodospec.ru

Living in your own home will be comfortable if the owners have provided all the necessary conditions for this. Few people are already attracted by the options with the delivery of buckets of water from a well, with a boardwalk toilet on the site. All this is permissible for dacha conditions with periodic visits for the weekend, but it looks like a complete anachronism if the family lives in the house permanently. This means that normal housing must be equipped with water supply and sewerage. It's good if in locality there is a possibility of connection to central highways and collectors. But such cases are quite rare, and more often it is necessary to create completely autonomous systems.

Water supply is a separate multifaceted topic, and in this case we are interested in the creation of an independent sewerage system. Discharge of untreated waste water into the environment is strictly prohibited. This means that it is necessary to install special structures or devices for collecting, settling, cleaning, clarifying wastewater. In the practice of private housing construction, the optimal solution to this issue is the use of special containers - septic tanks. Such an element of an autonomous sewage system can be built on their own or purchased ready-made. This publication will consider how to choose a factory-made septic tank, that is, what criteria for evaluating a product should be paid special attention to.

What is a septic tank. The principle of its action

A septic tank is the most important element of an autonomous sewage system or sewage treatment plant... And while it is not a complete wastewater treatment scheme in and of itself, its role is extremely important.

The main purpose of any septic tank is to collect all sewage from a house (group of houses), settle them and preliminary biological treatment of varying degrees of depth. The effluents that have gone through such a cycle are discharged into devices or structures of soil filtration, or are subject to regular pumping out using special equipment. In any case, it excludes the entry into the environment of polluted effluents that pose a chemical and bacteriological danger to it.

In fact, a septic tank is always a storage tank isolated from the ground, and can consist of one or several chambers. The diagram of the simplest single-chamber septic tank is shown in the figure:

Sewer drains from the house are fed through a pipe (item 1) by gravity, for which a certain slope is observed during laying (about 5 ° or 20 ÷ 30 mm of a drop for each running meter of the pipe). The septic tank chamber (pos. 2) has reliable waterproofing or is made of completely waterproof materials.

Solid inclusions under the action of gravitational forces settle to the bottom in the form of silt (pos. 3). Those impurities that have a density lower than that of water, on the contrary, float upward, forming a film or crust. Thus, there is a spontaneous stratification of the effluent.

In the same chamber, the processes of biological decomposition of human waste are constantly taking place. To activate these biochemical reactions, special anaerobic bacteria help to process organic matter into inert mineral sediments, gases that are discharged outside, and clean water. At the same time, this should lead to the death of the entire pathogenic microflora.

The water that has received such cleaning and clarification is transferred through the overflow pipe (item 4) to the filtration section. The water intake is organized so that it is produced from the central part of the stratified liquid, preventing the overflow of the floating crust. For this, the lad is supplied with a vertical section constantly submerged in water.

Final soil post-treatment can be organized in different ways. In this case, a filter well (pos. 5) with a drainage layer below is shown. However, it can be an underground filtration field using special perforated pipes. and Filtering or absorbing trenches are used. A special infiltration unit, the so-called "tunnel", can be purchased. The choice of a specific type of final soil filtration depends on the level of wastewater treatment, the type of soil, the height of the groundwater, the depth of soil freezing, etc. - in any case, a specialist recommendation is required here.

The filtration module (well, tunnel, field, etc.) is no longer considered as a septic tank chamber - it is the final link in the autonomous sewerage chain. Sometimes, when using septic tanks with multi-level purification, even storage tanks are used, the water from which can be consumed, for example, for irrigating a personal plot.

Single-chamber septic tanks, I must say, do not differ in a high degree of wastewater treatment. They are usually used for small volumes of wastewater (not exceeding 1 m³ per day) and in the event that fecal sewerage is not discharged into the septic tank. Otherwise, it simply will not cope with its direct task of full cleaning before infiltration, and the sewage machine for pumping out will have to be called too often.

The optimal solution is multi-chamber septic tanks. An example is shown in the diagram:

Sewage drains through a pipe (item 1) enter the primary chamber (item 2), which in this case serves mainly for settling the liquid, its stratification into light and heavy insoluble fractions. The main volume of the silty sediment accumulates here (pos. 3).

Through the overflow pipe (pos. 4) with a blocker (water seal) system, the drains, which have partially passed the initial cleaning, enter the second chamber (pos. 5). This compartment (often called a methane tank) is designed for biological water purification under the action of anaerobic bacteria. The decomposition of chemical organic components into solid insoluble neutral sediment (item 6), water and a gaseous component, which goes out into the ventilation pipe (item 10), takes place. This achieves a much higher degree of purification of any domestic wastewater, including fecal matter.

Further, through the overflow pipe (item 7), the purified water passes either into the infiltration device (in this case, a well is shown, item 8), with a filled drainage layer (item 9), or into the third chamber of the septic tank, where the final clarification takes place and subtle settling.

Often, the second or third chamber is used for more fine cleaning with aerobic microorganisms, for which it is envisaged to saturate it with oxygen - aeration, that is, the periodic passage of small air bubbles. For this, septic tanks are equipped with special aerator compressors, which, however, will require power supply.

To equalize the pressure in the compartments of the septic tank, they are connected by an air duct (pos. 11). Inspection and cleaning necks, closed by hatches, are required.

If increased requirements are imposed on the level of water purification (for example, for the possibility of its secondary use for technical purposes or if such conditions are put forward by the local sanitary and epidemiological service), then the septic tank can also be equipped with a biofilter, with a special mineral or polymer filler. The biofilter can be one of structural elements the last chamber of the septic tank, itself is such a final compartment, or it is a separate module that is installed after the septic tank in front of the filtration field or storage tank for purified water.

In septic tanks with a biofilter, the maximum high degree of water purification from sewage effluents is achieved, and such systems can already practically be classified as local treatment plants (VOC). Naturally, the cost of such installations is very high.

In conditions individual construction septic tanks were most often made of reinforced concrete rings, or they were built independently with the excavation of the necessary containers and cementation of their walls. Both options have a characteristic drawback - the difficulty in ensuring the complete sealing of the septic tank chambers from the surrounding soil, the need for constant monitoring of the state of joints, places of passage of pipes, etc.

But nowadays, a wide range of ready-made engineering solutions made from modern materials is on sale. Most often this is a multi-chamber design assembled in one housing, but it can also be modular.

Septic tanks differ among themselves in terms of total volume, productivity, dimensions, material of manufacture, layout, and other parameters. All this is important to consider when choosing a specific model.

Where is it allowed to place a septic tank?

Before purchasing a septic tank, you need to decide in advance on the place of its future installation. Not only is this very often - a very impressive structure in size - the location of such a treatment plant must comply with certain rules prescribed by regulatory documents - SNiP 2.04.03-85, 2.04.02-84 and 2.04.01-85, SanPiN 2.1.5.980 -00 and 2.2.1 / 2.1.1.1200-03. If desired, all these documents are easy to find on the Internet.

• These requirements were not invented out of nowhere - any septic tank is an object of potential environmental or man-made threat, which may be as follows:
• Flooding of the soil and foundations of buildings and structures due to a breach of the tightness of the container itself or the connection of pipes.
• Contamination of the territory of the site in case of overflow of the tank, for example, due to untimely pumping of accumulated silt deposits or due to natural phenomena - floods, abundant melting of snow, prolonged rains.
• Penetration of liquid waste and microbiological cultures carried by them into water sources or into nearby aquifers.
• Penetration of unpleasant odors into living quarters.
• Organic poisoning of the fertile soil layer, leading to the death of plants.

So, when choosing the location of the septic tank, adhere to the following standards:

• The distance to the foundation of a residential building should be at least 5 meters, from other outbuildings - at least one meter. In exceptional cases, when a closed-type VOC is used with complete biological processing of waste, the distance to a residential building can be reduced, but this issue requires additional approval.
• The most important parameter is the remoteness of the septic tank from the water source. If this is a well that feeds from the upper aquifers, then the distance should be about 50, and sometimes, with light sandy soils, even 80 meters. The distance to a deep water well is at least 25 meters. If the relief of the site allows, then the septic tank should be installed lower along the slope - this way the probability of effluent penetration into the aquifers will significantly decrease.

The exact distance should be determined each time individually, based on the study of the soil and the existing relationship between the aquifers and its filtering layers.

• Water pipes should not run closer than 10 meters from the septic tank.
• The minimum distance from a stagnant body of water (lake, reservoir, pond) is 30 meters, from a surface stream or river - 10 meters.
• If a highway with busy traffic passes near the house, then the minimum distance from it is 5 meters.
• There should be no trees or bushes around the septic tank within a radius of 3 meters. Firstly, plants can get intoxicated from oversaturation of the soil with organic matter and die. Secondly, this distance prevents the likelihood of damage to the container by the root system of trees or bushes.
• Provision should be made for a distance of at least 2 meters from the border of the adjacent plot. And at the same time, of course, all the above listed norms must be observed, regardless of the fact that buildings, trees, water intake points are not yours and are located outside the fence. In general, of course, in order to avoid misunderstandings in the future, the installation of a septic tank should be "amicably" coordinated with the neighbors.

As you can see from their listed requirements, finding the optimal place for installing a septic tank may not be so easy. In this case, it should also be taken into account that for regular pumping it is necessary to provide an access road for the sewage truck.

If the optimal place is found, then this does not mean at all that you can immediately proceed to installing a septic tank. The device of a structure of this type necessarily requires the preparation of a project, which is coordinated with the local sanitary and epidemiological service. When drawing up a project, specialists must take into account all the features of the site and the nature of the soil in order to already accurately determine the required distances to other objects.

The construction should be carried out exactly in accordance with the project - the "initiative" of the owners revealed later will be considered as serious administrative offense with all the ensuing consequences.

How much septic tank is required

The next decisive stage in the selection of the necessary septic tank is to determine its volume, so that the maximum purification of sewage drains, the complete decomposition of organic components is ensured, and a rapid overflow of the tank is excluded. At the same time, reasonableness in the approach to choice must also be observed - a septic tank that is too large will cost much more, it takes much more space, its installation will require serious labor.

There are several methods for calculating the required capacity of a septic tank, but all take into account the time required for a complete settling process and primary decomposition of organic matter. For example, you can give the following, rather "heavy" formula:

W- the required volume of septic tank chambers per person;

Q- the average consumption of wastewater, cubic meters per day;

t- time required for cleaning and settling wastewater (days);

WITH- concentration of unsettled suspensions at the outlet of the septic tank, mg / l;

N- standard indicator of drainage for each family member, l. per day;

T- average temperature of wastewater, ° С.

The concentration of suspended matter is taken from the table, based on the average temperature of the wastewater and the average water consumption per person per day:

Concentration of non-settled suspensions at the outlet, mg / l	Average temperature of wastewater, ° С	The required settling period of effluents (days) depending on the rate of drainage per person (l / day)
		50	100	150	200	300
50	7	11.1	6.4	4.6	3.5	2.4
	10	10.3	5.8	4	3	2
	15	9.5	5.2	3.5	2.6	1.6
	20	9	4.8	3.2	2.8	1.4
70	7	7.7	4.5	3.2	2.4	—
	10	7.2	4	2.8	2.1	—
	15	6.6	3.6	2.4	1.8	—
	20	6.2	3.3	2.2	1.6	—
100	7	5.2	3	2.1	1.6	—
	10	4.8	2.7	1.9	1.4	—
	15	4.47	2.4	1.6	1.2	—
	20	4.2	2.2	1.5	1.1	—
150	7	3.3	2	—	—	—
	10	3.1	1.7	—	—	—
	15	2.9	1.6	—	—	—
	20	2.7	1.4	—	—	—

The formula looks "intimidating", includes the construction of indicators to complex degrees, which requires a special engineering calculator, and it is very doubtful that at least one owner of a private house will be found who will resort to such calculations. But it is quite possible to follow a simplified path.

Sanitary standards require that the drains in the septic tank go through at least a three-day cleaning cycle. This means that the cameras of the device must contain three times the amount of water consumed by all family members.

W = 3 ×n× Qn

n- the number of family members.

Qn- average consumption per person.

There is another formula that is often used to calculate the volume of two-chamber septic tanks, which also takes into account a certain probability of maximum use of the entire planned flow rate by all consumers (this, you must admit, also does not happen so often).

W = (n × Qn+ Qn) × 2

This means that everything is calculated simply if you know the base value - how much water each person spends per day. But this is already a value - rather "unstable".

It is generally accepted that in the average statistical reality, the daily consumption is 200 liters per person. However, this indicator is far from always correct. Consumption can be lower, for example, in houses without bathrooms or showers. And if the house has all the "conveniences", and in addition to all this, modern household appliances are installed that use water (washing machines, dishwashers), then the consumption will be much higher.

In addition, it is necessary to take into account the likelihood of an increase in the number of consumers, temporary (arrival of guests or even permanent (expansion of the family. The septic tank is laid for many years in advance, that is, a certain reserve, at least 30%, is necessary anyway. and because in the period between pumpings, the capacity of the septic tank gradually decreases due to settled silt deposits.

Below, the reader will be offered a convenient calculator that allows you to quickly and with a sufficient degree of accuracy determine the required volume of a septic tank. It will be necessary to indicate the number of water consumers, and in one of the initial data request fields, tick the necessary options - the presence of some types of plumbing or household appliances and the approximate mode of their use.

Go to calculations

Such a calculation is applicable for a septic tank, built on its own, and for a ready-made purchase. If an independent construction is planned, then it is necessary to take into account that the calculated volume must be correctly distributed between the chambers. With a single chamber - everything is simple. In a two-chamber, 75% of the volume should be in the primary chamber, the remaining 25 - in the second. In a three-chamber, 50% of the capacity is given to the first chamber, and 25 to the second and third.

In the purchased septic tanks, of course, this ratio has already been taken into account by the model developers.

It is customary to approach the question of the number of cameras as follows:

A- a single-chamber septic tank, with subsequent output to the filtration fields or to a drainage well, will be sufficient with a total daily drainage not exceeding 1 m³.

B- a two-chamber septic tank is usually purchased if the daily volume of wastewater is in the range from 1 to 10 m³.

V- a three-chamber septic tank is required for large volumes of wastewater, over 10 m³ per day.

This is a recommendation, and in the case of small volumes, it is not considered a rule. That is, and if not too high level flow rate, you can purchase a compact two- or even three-chamber septic tank, equipped with a biofilter - such models are on sale. The quality of water purification from this will only increase. In addition, it is quite possible that local requirements of the sanitary-epidemiological or environmental service may directly indicate the mandatory use of septic tanks of one design or another.

Additional criteria for choosing a septic tank

The dimensions of the septic tank and its layout

Of course, the size of the septic tank primarily depends on the required volume of chambers. However, it is often possible to choose from a commercially available model, with approximately the same volume and an equal number of cameras, a model of vertical or horizontal design.

First of all, it is necessary to proceed from the area of ​​the site that can be allotted for the installation of a septic tank. Naturally, a horizontal septic tank will require more space. But on the other hand, to install the vertical model, you will have to dig a deeper pit.

Here, the depth of winter freezing of the soil is also taken into account. It is clear that in order for the septic tank to function year-round, it is necessary to prevent the liquid from freezing in it, that is, to place it so that the accumulating drains are located below the freezing level (this value is easy to find in any local construction or hydrometeorological organization).

If the soil freezes to a great depth, then, of course, the vertical model will be the best option. But if a high location of aquifers is noted on the site, then, of course, preference should be given to the horizontal one.

The general problem of volumetric septic tanks is "floating", pushing them up during seasonal temperature changes. To avoid this phenomenon, it is recommended to install treatment plants on concrete slabs placed underneath and tie them to them with anchor ties. A vertical septic tank wins in this regard - it is more stable due to a smaller cross-sectional area in plan.

When choosing a model, especially a horizontal version, the required height of the revision necks must be taken into account - when installing a septic tank at a great depth, they must reach the level of the ground surface.

Taking into account the peculiarities of the soil on the site

The choice of a septic tank is seriously influenced by the nature of the soil on the site.

• With light sandy soils, with a deep location of aquifers, the best choice will be a septic tank with the output of the water that has passed the initial purification to the filtration fields. This is the most economical option.

• If the site has clayey soil with low drainage capacity, then, most likely, you will have to think about purchasing a full-fledged biological or biochemical treatment station. Water that has gone through a full cycle of such post-treatment can already be discharged to the surface, for example, into a drainage ditch, or it can accumulate in an accumulation tank with periodic pumping to the ground or for household needs.

The cost of such complexes is quite high, and they usually provide for the installation of additional pumping equipment.

Another option is an independent organization of the filtering field, but this is a very time consuming and costly option. It is necessary to run away and take out a large volume clay soil, to replace it with sand and gravel backfill - the work is extremely large-scale and expensive. They resort to this approach only in cases where it is impossible to use a septic tank with biochemical purification.

• If the site is marked proximity aquifers, then soil filtration of wastewater without preliminary biochemical treatment is completely excluded.

The septic tank must be completely sealed, have a special system of valves that exclude the ingress of groundwater into the chambers, equipped with biofilters, pumping equipment for pumping purified water from a well to an irrigation dome or an artificially made surface filtration field. Surely, all these requirements will be presented to the owner of the site when drawing up the project documentation.

Septic tank material

The septic tanks on sale can be polymer or metal. Each variety has its own advantages and disadvantages.

• The simplest metal septic tanks are quite affordable. Their main advantage is considered to be a large mass - such a reservoir is less susceptible to "floating" than others. However, the massiveness also creates a number of difficulties associated with transportation, handling and installation work - in most cases, special equipment will be required.

A metal septic tank must necessarily have a high-quality waterproofing and anti-corrosion treatment, both outside and inside, otherwise it will not last long in aggressive operating conditions.

Another drawback is that due to the pronouncedly high thermal conductivity of the metal, such septic tanks are more at risk of freezing, even if they are located below the level of soil freezing. This means that you will have to think over the issue of their effective thermal insulation, for example, using mineral wool. All this is an additional cost of material resources and time.

Nevertheless, metal septic tanks are quite widespread, especially among summer residents, apparently due to the simplicity of the design and the low price.

• Plastic septic tanks are currently the most popular. They represent a complete structure, usually reinforced with ribs of strength, relatively small in weight, which greatly facilitates its transportation and independent installation.

1 - septic tanks made of polyethylene low pressure(HDPE) - the lightest of all, relatively inexpensive. They are molded using an almost seamless technology, in any configuration. which ensures guaranteed tightness of containers. There are restrictions on maximum effluent temperatures.

2 - cleaning stations made of polypropylene - more resistant to abrasive abrasive load, to accented impacts .. The density of the material is even slightly lower than that of HDPE. They have excellent resistance to high and low temperatures - they can well be used for cleaning hot drains.

3 - septic tanks made of fiberglass, the most different and reliable among all polymer. The material of manufacture has a pronounced chemical resistance even to aggressive organic solvents, so such containers can be used to clean industrial wastewater. Glass price plastic septic tanks- the highest (with other equal parameters).

All modern plastic septic tanks are designed for long-term operation - up to 50 years or more. Their common disadvantage stems from their dignity - the small mass of the container makes it more likely to "float" to the surface, that is, the issue of fixing the septic tank in the ground should be thoroughly considered.

A brief overview of septic tank models

And at the end of the publication - short review models of the most popular manufacturers among Russian consumers.

Series "Tank"

Probably, these are the leaders in popularity, due to the low price, simplicity of the device and operation, high performance sewage treatment.

The septic tanks have a characteristic ribbed shape to increase the rigidity of the structure, and the thickness of the HDPE walls reaches -10 mm in flat areas, and up to 17 mm at the peaks of the ribs. This guarantees long-term trouble-free operation of the septic tank, for a period of at least 50 years.

The assortment of production includes models designed for both small families(1 ÷ 3 people), and for a large number of water consumers (up to 9 ÷ 10). In addition, the modular design allows you to assemble common systems any required performance.

If desired or if necessary, a biofilter can be easily built into the septic tank, and it is possible to install pumping equipment.

The minimum volume is 1.2 m³, with a capacity of up to 600 l / day. Moreover, the mass of such a septic tank is only 85 kg, that is, it is not at all necessary to use construction equipment to install it.

Biotank series

Septic tanks "Biotank" are a full-fledged autonomous treatment plant, from which it is permissible to simply divert water to the relief.

This is a four-chamber design of vertical or horizontal design, with a full cleaning cycle, including aeration and a biochemical filter. It is produced in various modifications, both with forced pumping of water, and with its movement by gravity.

The range of products includes models with a capacity from 1000 to 3000 liters (from 3 to 10 consumers).

Septic tanks "Triton T"

Inexpensive, simple in device, but at the same time - efficient and reliable septic tanks of the Triton T series. They are a three-chamber horizontal container made of durable polyethylene with a wall thickness of 14 to 40 mm.

The centrally located neck provides access to all three container compartments. The neck can be extended with cylindrical segments 500 mm high. The installation of a special well for the pump is provided.

The model range is from 1 to 40 m³, that is, such a septic tank of the required volume can be used to create a sewerage system for several houses at once.

Cleaning stations "Topas"

Septic tanks "Topas" are full-fledged autonomous sewage systems that deeply purify water, after which it is allowed to discharge it onto the ground, filtration fields or even natural flowing water bodies.

The four chambers of the plant are equipped with all levels of purification - from conventional sedimentation to biochemical filtration. Aeration with complete oxidation of organic matter is provided. It is possible to independently regularly clean the chamber from silt deposits using an airlift or a drain pump, without calling a sewer truck.

The produced assortment includes models designed for a different number of consumers - from 5 to 20 people.

Video: installation of a local sewage treatment plant "Topas"

It is characteristic that all the models discussed above are Russian-made.

Paying attention to all manufacturers is very difficult on the scale of one publication. You can mention deserving positive feedback septic tanks of foreign production "Uponor Bio", "Alta Bio", "Fast", "Evo Stok Bio", domestic "Unilos", "BIOzon", "Topol", "Chistok". Tver septic tanks show themselves well in everyday operation, but, however, their installation should be carried out exclusively by specialists - there are too many nuances in the installation and debugging of equipment.

And the last thing. If a family lives outside the city only occasionally, on weekend visits, then a full-fledged septic tank is most likely not needed, especially since biocultures in it can die simply due to insufficient nutrient medium. In this case, it would be wiser to install a so-called storage septic tank, otherwise - just a sealed storage tank of the required volume. an example of such a model is the septic tank "Triton N", with a capacity of 1000 or more liters.

The process of biological decomposition and settling of effluents will also take place in such a septic tank. But, of course, we are not talking about any discharge of water to filter fields or drainage wells. It's just that as the tank is full, you will have to call a sewer truck.

Home improvement is a serious task, especially if the building cannot be connected to city-wide utilities. In this case, they build local systems, including a local sewerage system. But before starting construction, you will need to develop a project and carry out calculations. Let's figure out how to calculate the volume of a septic tank.

Local sewerage systems are equipped with a treatment plant. Most often, such an installation is a septic tank with soil purification. For the system to function properly, it is important that the tanks are large enough, as otherwise, the water will not be well cleaned. Let's figure out how to calculate the volume of a septic tank.

How does it work?

To understand how much a septic tank should have, it is worth getting to know how this installation functions. Cleaning proceeds like this:

• the water supplied through the pipeline enters the first settling tank, where primary settling takes place, during which the heaviest and largest particles are deposited;

• then the water, being freed from the largest debris, flows through the overflow pipe into the second settling tank, where the settling process is repeated, only now lighter and smaller particles of debris are precipitated from the water;
• Well-settled water is supplied to the soil after-treatment - to the filter well or to the filtration sites.

As can be seen from the description, the main method of purification in conventional septic tanks is sedimentation. And in order for the suspension to settle well, it must be at rest for a long time. In other words, the contaminated liquid must remain in the tanks of the treatment plant for a long time, only in this case it will have time to settle well.

It has been experimentally found that in order to achieve an acceptable level of purification, the liquid must be inside the sedimentation tanks for at least 72 hours. Therefore, the tanks must also accommodate the amount of effluent generated at the serviced facility during this time.

What factors need to be considered?

As it becomes clear from the above, the volume of the tanks directly depends on how much water the residents use. The consumption is affected by:

• the number of users, that is, how many people live permanently, and also come periodically. Naturally, at the facility for a family of 3-4 people, the amount of sewage will be significantly lower than in the residential building of the holiday home, designed for 20 guests and 15 staff;
• home equipment with plumbing. It is clear that in a house equipped with a jacuzzi with a volume of 350 liters, the volume of drains will be greater than in a house in which only a shower cabin is installed, even if there will be an equal number of people living in these houses.

Formula

The easiest way is to calculate the volume of a septic tank using a simple formula:

V = 3 * n * Q * 1.2

In this formula, symbols indicate:

• V is the volume of sedimentation tanks;
• n is the number of people;
• Q is the daily volume of wastewater.

The numbers indicate:

• 3 - the duration of the cleaning cycle takes three days;
• 1.2 is the correction factor required to increase the volume of tanks in case of a temporary increase in the volume of wastewater, for example, in case of the arrival of guests.

Advice! If the family is distinguished by hospitality and several people are visiting them, it is worth increasing the volume of the septic tank using a correction factor of 1.5.

How to determine the volume of effluent?

If the determination of the main variables included in the formula does not cause difficulties, then problems often arise with the answer to the question of how to determine the daily volume of effluents. This indicator depends on the number and type of plumbing.

The standard daily consumption is 15 or 20 decaliters. If the facility does not have a bath, but only a shower cabin is installed, then the average daily consumption can be taken as the figure of 15 decaliters. In the presence of a bath, this figure should be increased to 20 decaliters.

Advice! If the house is equipped with a standard set of plumbing, but all family members are accustomed to taking a bath every day, then the daily volume of wastewater per person will be 30 decaliters.

Calculation examples

Let's give a couple of examples of how you can make a calculation optimal size sedimentation tanks

Example one

Conditions: A local sewerage system is being built for a family of five members. The house is equipped with a standard set of sanitary ware, the daily volume of wastewater per person is standard - 20 decaliters. We calculate according to the above formula: V = 3 * 5 * 20 * 1.2 = 360 decaliters or 3.6 m³.

Example two

Conditions: you need to determine the optimal volume of a septic tank for a summer residence, where 3 people will have a rest in the summer, and often 1-2 people will come to visit. The dacha is equipped with a shower, so the daily volume of wastewater will be 15 decaliters: V = 3 * 3 * 15 * 1.5 = 202.5 decalitres or 2.02 m³.

Example three

You need to calculate the volume of the treatment plant for a motel with a capacity of 20 guests. Since motels do not install baths, the daily consumption can be taken as 15 decaliters. And since, in addition to guests, the motel has attendants, it is worth using the maximum multiplying coefficient: V = 3 * 20 * 15 * 1.5 = 1350 decaliters or 13.5 m³.

How many cameras should there be?

The number of chambers, as well as the total volume of the treatment plant, directly depends on the volume of wastewater to be disposed of. For private residential buildings (houses, summer cottages), as a rule, two sealed sedimentation tanks are built.

In addition, a third element is included in the system; this can be a filter well or filtration platforms. If a spacious septic tank is being built to serve 15 or 20 users, then the number of sedimentation tanks should be increased.

When building a two or three-chamber installation, the dimensions of the chambers are made unequal. So, the largest should be the receiving compartment. In a two-chamber version, it should occupy 75% of the total volume, since it is in this compartment of the septic tank that the heaviest and largest inclusions are deposited. If a three-chamber version of a septic tank is being built, then the receiver should account for 50% of the total capacity, and the two remaining chambers are made the same.

Advice! Not in all cases, cameras are made different in volume. For example, when a sewage treatment plant is built from reinforced concrete well rings or euro cubes, all compartments of the plant will be the same.

What can be the result of errors in calculations?

If the volume of the sedimentation tanks is not determined correctly, the unit will work worse. So, if the capacity of the installation is insufficient, then the liquid will not have time to settle properly and poorly purified water will be supplied to the outlet.

This will lead to the fact that the soil filter used for additional treatment will quickly silt up and it will become worse to filter the water. To restore the system operation will require laborious repairs.

It is inexpedient to build sedimentation tanks with a large volume reserve for economic reasons, since the construction of a spacious septic tank will cost much more than the construction of a compact model.

So, in the process of designing a local sewage system, a septic tank is calculated. It is very important to do this work correctly, as the quality of the treatment plant will depend on it. If you plan to buy a ready-made septic tank, then you do not need to carry out calculations, the manufacturer must indicate the performance parameters of the model in the documentation.