Sewer pit in a private house with their own hands. How to make a drain hole on your site

During the construction of a cottage or country cottage, the arrangement of the sewer system is a priority. A cesspool in a private house is designed in accordance with the standard standards described in SNiP and SanPin.

Cesspools are classified according to the material from which they are made, design and principle of operation.

According to the material, the following types can be distinguished:

1. Plastic. Equipped from professional plastic tanks. The volume of the pit is up to 1 cubic meter, then the use of a polypropylene barrel is allowed;
2. Metal. Similar to plastic, they are built from ready-made metal tanks;

   

3. Concrete. These are cesspools made of concrete rings. This design is durable and low maintenance. Concrete is impact resistant stool and aggressive liquids draining into the drain;

   

4. From tires. One of the "handicraft" ways of arranging a cesspool. To create a cesspool from car tires used tires from cars and trucks. They are interconnected with bolts;

   

5. Brick. Great for arranging large cesspools. Completely sealed. Ceramic building materials are well tolerated by prolonged contact with water and are not susceptible to deformation under the influence of earthen masses.

   

By design, cesspools are classified as:

1. Closed. Fully sealed constructions. They consist of a closed bottom and strong walls. Such containers are environmentally friendly and suitable for installation in small areas;
2. Open or leaky. According to the rules of Sanitary Control, such a device is allowed only if the total volume of waste per day does not exceed 1 cubic meter. These pits do not have a bottom and some of the waste goes into the soil and groundwater. This allows you to carry out sewage cleaning less often than with closed tanks, but threatens the environment.

According to the principle of operation, all cesspools are divided into single-chamber, multi-chamber and septic tanks. Single-chamber - standard structures consisting of one compartment. It is both a draft drain and a sump. This is the easiest way to equip a drain, but it requires regular cleaning. In it, effluents are simply stored for a certain time before sewage cleaning.

Multi-chamber - cesspools, consisting of several compartments. The standard scheme is a connection of single-chamber tanks with nozzles. Waste from the house or other consumer points is dumped into one, and pre-treated waste flows into the second. The effluents are in the sump for several days, after which they are additionally cleaned and drained outside the site.

Septic tanks are professional multi-chamber devices. They consist of tanks separated by nozzles and filters, pumps that pump wastewater at a certain rate and treatment facilities (biological filters). The main advantage of using a septic tank for a cesspool is its efficiency. It is not just a liquid accumulator, but also a purifier. Many owners use settled water in the future for technical needs.

Calculation of the required volume of the pit and its geometric dimensions

The volume and geometric dimensions of the cesspool in a private house depend on the number of consumers living and connected to the sewer. It is standardly considered that 1 adult consumes 0.5 cubic meters of water per day. The child, respectively, is half as much - 0.25.

The formula is used to calculate:

V * n \u003d Vya, where V is the daily volume consumed by one person, n is the number of residents, and Vya is the required volume of the cesspool. For example, if there are three adults and 1 child in the house, the formula would look like this:

0.5 * 3 + 0.25 * 1 \u003d 1.75 m 3. The resulting values ​​are always rounded up. In our case, this is 2 cubic meters. From the obtained values ​​​​determine the desired dimensions.

Rules for choosing the depth and diameter of the pit:

1. The minimum drain depth must be at least 2 meters. 1 meter is allotted for the release of gases and freezing of the soil;
   2. The maximum depth is no more than 3.5 meters. Most sewage trucks equipped with hoses, the length of which is 3 meters. Exceeding this indicator will significantly complicate the processes of wastewater treatment from silt and solid accumulations;
2. The width depends on the selected depth and standard sizes materials chosen for the construction of the drain.

Location on the site

Cesspool closed type more often used in a residential private house, because, it can be placed much closer to the living space than an open one. All requirements for choosing a place are described in detail in “Urban Planning. Planning and development of urban and rural settlements”, decree 360-92 (Ukraine) and SanPiN 42-128-4690-88 (Russia).

Primary requirements:

1. The distance from the residential building is at least 20 meters. A distance of 15 meters from the non-residential premises is allowed. Separately, it is indicated that if the basement exceeds the area of ​​\u200b\u200bthe house, then the countdown starts from the wall of the underground building;
2. From a reservoir or well, you should retreat from 30 meters (closed pit) to 50 (open tank);
3. A distance of 2–4 meters is maintained from the road and the fence;
4. According to the rules of good neighborliness, a cesspool should be separated from the neighboring area by at least 10 meters.

In some cases, it is also indicated that the waste tank must be at least 5 meters away from the garden or garden. It must be remembered that failure to comply with these requirements entails administrative liability.

Installation of a cesspool

The arrangement of the cesspool is carried out in several stages:

1. Pit preparation;
2. Tank installation;
3. Connecting sewer pipes;
4. Drain backfill.

In the selected location of the site, a place is planned for the future cesspool. The pit is excavated with special construction equipment or manually. Its diameter should slightly exceed the dimensions of the tank for arranging a cesspool. This will allow you to more thoroughly seal the container and insulate it.

Regardless of the type of pit design chosen, the bottom of the pit must be reinforced with crushed stone and a sand cushion. The first layer of sifted river sand is poured, after it - fine gravel and then - stones of a coarse fraction. The walls of the pit are covered with waterproofing material. In cold regions, textiles or agrofibre are also installed on top of the waterproofing to protect against freezing of the soil.

The organization of the sewer system of a private house is a priority after the construction of the building. Without it, it is impossible to imagine the functioning of the plumbing, shower and toilet in a residential building. Building a cesspool with your own hands is a fairly simple task that even a beginner can handle.

1. Choosing the right place. The cesspool must be placed on a private plot, at a distance of at least 5 m from the buildings. Otherwise, the foundation may be washed out by water coming from the drain pit after filtration. The distance from the pit to the water source on the site should be at least 20–30 m. If the size of the site does not allow maintaining the required distance, it is advisable to make the pit completely sealed. This will require more frequent sewer cleaning, but it will completely isolate the soil on the site from harmful wastewater.
2. Volume calculation. Depending on the number of family members living in a private house, as well as the time of residence (seasonal or permanent), the sizes may vary. It is estimated that an average person needs 150–200 liters of water per day, including showers and toilet flushes. When calculating, you need to include greater value in case of visiting guests or relatives.
3. When planning a cesspool, you need to immediately decide whether waste from the plumbing and toilet will merge into one place. In some cases, separate pits are erected: for a toilet - with a sealed bottom, for waste water - in a pit without a bottom.
4. The choice of building material. You will need the following materials:

• concrete rings.
• Brick.
• Concrete.
• Plastic container.

First of all, on the site you need to lay a pipe from the house to the future sewer container. It is placed in a trench, which has a slope from the house to the drain hole.

The depth of the trench should be below the level of freezing, or it is necessary to well insulate the hole for the system for draining water into the sewer:

• Lay a sand and gravel "cushion" at the bottom of the trench.
• Place insulation on top, then waterproofing material.
• After laying the pipe from above, fix the edges of the waterproofing and insulation, pour in a sand-gravel mixture and lay the soil.

Such measures will prevent the deformation of the drain pipe leading to the sewer.

Pit preparation

• After choosing the location of the drain pit, earthworks begin. If the sewerage in a private house is equipped with a brick, concrete mortar or plastic container, it is necessary to prepare a foundation pit right size. This can be done both with the help of hired equipment, and on your own, spending a certain amount of time and effort.
• If concrete rings are chosen as the building material, it is enough to put one of them in place of the future drain pit. For earthworks, you need to use a convenient shovel with a short handle. First, the earth is removed, being in the middle of the concrete ring. Gradually remove the earth from under the concrete walls of the ring, gradually lowering it into the pit. After the ring is completely immersed in the ground, you need to place the second ring on top of the first one and continue excavation.

When using this method, you need to keep at hand building level, with which it is necessary to correct the position of concrete rings in the horizontal plane.

• A brick cesspool requires a rectangular, square, or round hole in the ground, along the perimeter of which masonry is made to the very top. Below the freezing level, it is necessary to prepare a hole for entering the drain pipe from the house, and after its installation, seal the joint between the pipe and the wall of the cesspool.
• If it is planned to equip a sealed cesspool, then the bottom of the hole in the ground must be concreted using reinforcement. On the prepared bottom, laying of bricks begins around the perimeter of the pit. Experts recommend treating with a solution not only the junctions of the bricks, but also their side surface. This will give the reliability of the entire structure.
• If you plan to drain water into the soil, you need to create a natural filter, which includes not only a sand and gravel cushion, but also parts of a broken brick. The thickness of the filter layer should be at least 30–50 cm. This will protect the nearby soil from the harmful effects of the waste in it.
• From above they are laid: either a concrete slab, or wooden frame from metal sheets. In an impromptu hatch, it is necessary to provide an opening for periodic cleaning of the cesspool.

Arrangement of a cesspool made of concrete

A drain pit can be made by pouring concrete into the prepared formwork, but professionals suggest giving preference to concrete rings. They are easy to install, although they do require some effort to get them into place.

Concrete is reliable building material, allowing you to make drain pits, both with a sealed bottom and with a natural filter for water coming from the sewer.

Note! concrete structure perfectly withstands the loads arising from soil deformation in winter.

This hole can be covered with concrete slab or hatches of the desired diameter.

Drainage pit from a plastic container

In this case, a plastic container of the required volume is selected. If you cannot find the required container, you can combine two smaller containers using a connecting pipe. Even on the ground around the plastic containers, a reinforced frame is prepared from metal rods welded together. The entire structure is placed on a concrete bottom, and a concrete solution is poured on the sides, preventing soil pressure on the sewer in the winter.

Note! The need to fill the container with concrete arises when it is installed in unstable soil, and is determined individually for each case.

Usage plastic containers very convenient in that they already have hatches of a suitable hole for periodic cleaning of the drain pit.

Additional cleaning methods

It is advisable to regularly clean the cesspool. Chemistry can help with this. It includes: bleach; oxidizers; formaldehydes; special ammonium compounds.

The use of chemistry in each case should be determined by the type of cesspool and its location. It must be remembered that, although chemicals are effective and do not depend on the hardness of the water, as well as the impurities in it, they cause severe harm to the environment, so their use should be extremely dosed. These preparations may be presented as powder, liquid, or tablets.

In addition to chemicals, you can use an antiseptic to clean the drain pit. This method is more environmentally friendly than chemicals. Antiseptic and antibacterial preparations accelerate the processes of decomposition, naturally reducing the amount of waste.

Preventive measures to clean drain holes will help keep the sewer system in perfect order.

Video

Video on how to make a high-quality and inexpensive cesspool:

People tend to travel outside the metropolis, to the country, to be closer to nature, fresh air and earth. But there one unpleasant discovery awaits them - the absence of the usual urban amenities, one of which is sewerage. There is no centralized system traditional for the city, therefore, for a comfortable stay, you have to lay pipes for wastewater and get acquainted with such a concept as a drain pit in a private house.

The principle of operation of country sewerage

The modern dacha is fundamentally different from the village houses of the last century. Economic townspeople replaced toilets hastily knocked together in the yard with comfortable toilet bowls, installed showers, bathtubs, washing and dishwashers. The question arose: where should the dirty used water go?

This is how an elementary sewer system appeared: a set of discharge pipes that lead to a storage tank installed on suburban area outside the building. Different structures can act as a storage device: an expensive station biological treatment, a simpler device - a septic tank or cesspool, known since ancient times. Waste and sewage through pipes enter the store, from where they are taken out at different intervals by special equipment.

Regular pumping out of the contents of the waste pit is a prerequisite for its use. The only way efficient cleaning of the storage tank - call for vacuum trucks

Most vacationers, especially those who spend only their summer holidays in the country, dream of installing a suitable drive quickly and cheaply. Perfect option in this case, a do-it-yourself drain pit. For its construction, it will take several days and a minimum of costs - mainly improvised material: bricks, boards, cement.

Calculation of the volume of the drive

Before digging a pit, it is necessary to determine its dimensions, as well as the approximate volume of wastewater. It is generally accepted that 0.5 m³ of the total volume of the pit should be allocated for each tenant. But you need to take into account the incalculable consumption of water during water procedures and use household appliances, therefore a tank of at least 6 m³ is required for a family of 4.

The slope of the base of the pit towards the location of the hatch is necessary for the full pumping of sewage by sewage equipment - a specially provided hose that is lowered to the bottom

The size of the structure depends on the volume of incoming effluents, but there are certain boundaries. For example, the depth of a country drain pit should not exceed three meters, otherwise the sewage equipment simply cannot cope with cleaning. The width is usually 1-1.5 m, the length is 2.5-3 m.

Attention! The soil level should exceed the filling level of the pit by at least 1 meter. This is a kind of insurance against spillage of sewage beyond the boundaries of the pit.

Choosing a suitable construction site

It is important not to make a mistake in choosing a location. The question arises: how to make a pit for a drain pit, so that sanitary standards are not violated?

The diagram shows the approximate location of the drain tank in relation to residential building, water source and nearby obstacles

There are a number of rules:

• The minimum distance from the house to the drive is 5 m.
• The distance to the nearest water source is 30 m or more.
• The pit should be located in an open space, not fenced with buildings or a fence.
• A prerequisite is a good access road for a sewage truck.

Needs to be considered drain hole as an object of increased danger, so the playground and recreation areas should be located on the other side of the house.

An example of the construction of a brick pit

Stage #1 - earthworks and foundation

Digging a pit is a difficult and time-consuming process, so it is better to use an excavator if possible. The most convenient shape is considered rectangular or square, but pits and cylindrical configurations can also be found. During digging, the condition of the walls should be monitored: they should be even and protected from shedding.

If you haven't had to do it before brickwork, it is better to choose a building rectangular shape: straight walls and corners are easier to form

Features of the device of the drain pit largely depend on the material. Let us consider in more detail the construction of a red brick storage tank with a concrete bottom.

The bottom of the tank should be given a slight slope towards the hatch - for effective cleaning. The bottom layer is a 15 cm sand cushion, then a concrete layer, and finally a cement-sand screed.

Attention! Instead of a multi-layer base, you can install on the bottom reinforced concrete slab suitable sizes.

Stage #2 - building walls

The material for the construction of the walls is red brick, the mortar for laying is a mixture of sand and clay, which will later play the role of plaster. Masonry is done in the traditional way - with a half shift of the brick in the next row. The minimum thickness of the masonry is 0.25 m. brick walls partially permeable, but how to make a drain hole airtight? And it's very simple - you need to use bituminous mastic or similar waterproofing solution.

During the construction of the pit, a long ladder and any useful material at hand, such as boards and beams left over from the construction of the house, are used.

Attention! Bitumen-based mastics cover only absolutely dry walls.

Stage # 3 - installation of the overlap

The most durable is the reinforced concrete floor. Wood and plastic are not suitable, as they have a too short service life. It is better if the upper part of the structure is blocked from the sides by 0.3 m. The pumping hole should be located in the upper part, but not in the center, but on the side of the slope of the base. Design for concrete floor created in several stages. The first layer of mortar (5-7 cm) is poured, then iron bars are laid on it, covered with a second layer of concrete on top. When the overlap is completely hardened, it must be masked: covered with a thick film and covered with soil. Only the hatch should be visible from the ground.

Only the manhole cover remains visible on the surface of the earth. It can be made of concrete, plastic or metal.

As you can see, it is not difficult to make a brick drain pit, just basic skills in masonry and wall processing are enough.

Advantages and disadvantages of the structure

The advantages of a drain tank include the following factors:

• Ease of installation and maintenance. You can dig a hole and ennoble it yourself, and to clean it, just call the sewers.
• Independence of installation from soil type. In sandy soil, a clay castle is used for greater strength.
• Protection ground water from pollution. Concrete bottom and brick walls prevent runoff from penetrating into the ground, but if it seeps out, soil bacteria can handle the cleanup.

Before you dig a storage drain hole, you should also consider its negative sides. One of the tangible troubles is the periodically occurring smell of sewage. Regular cleaning will help eliminate this problem.

A well-equipped road leading directly to the waste pit is a guarantee of high-quality cleaning. Road construction is best done at the stage of building a house

It is necessary to get used to frequent visits to the sewers - 1-2 times a week. Only with frequent cleaning of the pit does silting occur. The service life of a brick drive is no more than 15 years, since the masonry slowly collapses under the influence of water. If for some reason the cesspool ceases to suit, you can install a more functional septic tank that performs mechanical and bacteriological wastewater treatment.

Thinking about manufacturing country water supply? Then you should know that in addition to it, you will also have to make a country sewer. By by and large, it differs little from the system of sewage conduits that are laid in the city - the difference between them lies only in the point of discharge of polluted water. If everyone in the city sewer pipes lead to treatment facilities(at least, this should ideally be the case), then in the country a drain pit is used as their role. It's about her, or rather about her self construction, and the conversation will go in this article, in which, together with the website, we will deal with its device, manufacturing technology and materials that can be used to create it.

How to make a drain hole photo

Drain pit: device and principle of operation

Structurally, the classic drain pit is a simple fixture that almost every person can make in the country - even special skills are not needed here. Moreover, it can be made from enough a large number improvised materials. This is on the one hand, but if you look at this device from the other side, then, like all technical devices, the drain pit has its own subtleties and nuances that you need to know. First of all, this device and the principle of operation - if you understand these points, then there will be no problems with the selection of materials for the pit, or with its direct construction. The classic drain pit consists of the following elements.

You can see more details about the device and the principle of building a drain pit in the country in this video.

In principle, this is the whole device - as you can see, a do-it-yourself drain pit does not differ in complexity of design. The principle of its operation looks even simpler - drains falling into the pit are simply absorbed into the soil. This is with regard to their liquid part - with solid waste, things are somewhat different. First, they accumulate at the bottom and do everything to clog the channels in the soil and prevent the rapid absorption of liquid - they kind of set themselves the task of making sure that they are constantly in the water. In the end, this will happen - when this happens, you just need to start adding special bacteria to the pit, which will liquefy the solid waste of human life.

Do-it-yourself drain pit in the country: what to make

As you already understood, the main element of the drain pit, which, in general, will have to be built, is a persistent wall that prevents the destruction of the pit. It can be made from various materials, which you can collect quite a lot - naturally, we will not do this and consider only the most common options. The task is not to poke your nose, they say, do it, but to clarify the principle, having understood which, you can independently select the material you need for the drain pit from what is available at the dacha.

In general, the principle is simple - you need to create some kind of container. How and from what you make it is now up to you. You need to go through the cottage well, and others warehouses- You look, something suitable will come across.

How to make a drain hole: a bottom filter and its purpose

Bottom filter - without it, not a single pit is able to serve long time- it is for this reason that the question of how to make the bottom of the drain pit needs special attention. There is nothing complicated here, you just need to know a couple of points, which, in general, extend the life of the drain pit in the country.

In principle, these are all the nuances associated with the manufacture of a bottom drain pit filter. They should not disdain, even during the construction of a drain pit small size- as mentioned above, it is able to increase the service life of an individual by two or even three times.

In conclusion of the topic about how a drain pit is made, I will say a few words about its close relative - a septic tank. They are distinguished from each other by the presence of several chambers in the second one, in which solid and liquid waste is separated. As a result, one liquid reaches the chamber in which water is absorbed into the soil, as a result of which the ducts in the soil are practically not clogged. Consequently, such a pit also serves without pumping out for a very long time - if you make a septic tank correctly, then you can use it for almost half a century. Read about how to do it in another article on our site.

Depending on the amount of drained water, you can choose suitable option:

• a pit without a bottom (drain) is a suitable option to make a drain in the bath;
• sealed cesspool - for a large number of drains;
• septic tank - for partial treatment and draining of wastewater.

Which is better - a sealed or drain cesspool?

If the daily amount of discharged water does not exceed one cubic meter, a drain pit can be used. This is convenient, for example, when organizing a drain in a bath. It is enough to dig a pit with a volume of 3 m³, lay a pillow of 30 cm of sand and 50 cm of stones on the bottom, strengthen its walls with brick, concrete or even tires and close the hole.

If much more water is drained, it does not have time to seep and be cleaned. Then you can make a completely sealed cesspool. Ready-made containers are sold, which can be immediately buried.

The only drawback of such a pit is the monthly pumping of waste.

A septic tank is the best cesspool

If the amount of discharge exceeds one and a half cubic meters per day, but it is unprofitable to order a monthly pumping out of the pit, the best way out is to make a septic tank in a private house. It filters waste quite well, polluting environment much smaller than the usual latrine with a pit. Ready-made systems are sold, which are enough to bury on the site, or you can do it completely on your own.

Advantages and disadvantages of a homemade septic tank

A do-it-yourself septic tank has whole line advantages over ready-made solutions:

The final cost is significantly lower;
+ does not require a large area for organization filtration field;
+ you can organize one septic tank for two houses;
+ depending on the type of wastewater, pumping is required every few years;
+ spend complete cleaning Maybe once every ten years.

But the disadvantages of such a septic tank are also present:

- significant labor costs - it is problematic to cope with the device of a septic tank alone;
- time - pouring cement into the formwork and its hardening takes about a month;
- additional equipment - to simplify the process, you will need a concrete mixer or a drill with a mixer.

Site selection

The requirements for a septic tank are the same as for a cesspool - no closer than 15 meters from the well and 30 meters from the reservoir. At the same time, do not forget about the neighbors - the distance to their well should also not be less. But to the house it can be placed almost close - 3 m from the foundation with a one-story building, and 5 m - with a two-story building. In addition, this is how the issue of insulating the drain pipe is solved - the greater the distance to the pit, the deeper you will have to dig a trench and insulate the pipe.

Be sure to take into account the direction of groundwater and flood water - they should not go from the septic tank to the house or well. At the same time, it is also undesirable to arrange a septic tank in the lower part of the site - melt and runoff water will flood it. To protect the septic tank from flooding or raise it above the groundwater level, it can not be buried completely in the ground, insulating the above-ground part to prevent freezing.

Step by step instructions on how to make a septic tank

After choosing a place for a septic tank, work begins on its organization. It is necessary to calculate the required volume of the main chamber and the overall dimensions of the pit. So, for four people, the main chamber will be at least 150x150 cm, and for five or six - 200x200 cm. In this case, the depth should be at least 2.5 m, but not deeper than 3 m. This is done for the convenience of future pumping. The second, or drainage, chamber cannot be less than a third of the main one.

If there is a shower in the house and it is used daily, the size of the chambers must be increased by another 50%. It is also better to leave a small margin, since the filling of the working chamber should not exceed 2/3 of the total volume per day. In addition, the drains in the working chamber should settle a little, and not immediately overflow into the drainage chamber. The optimal volume of a septic tank is the daily amount of drained water multiplied by 3.

1. After determining the size of the chambers, markings are made and a foundation pit is dug. The upper fertile layer is removed - it can be used to cover the septic tank and arrange the beds.



2. The trench for the drain pipe is dug at the same time as the pit. The slope of the pipe is 3 degrees per meter. So that the masses do not stagnate, the pipe must be laid without straight and sharp corners.
3. It is desirable to get to sandy or sandy soil. On the clay soil a sand and gravel pad is being made. First, 30 cm of sand is poured and tamped, and then the same amount of crushed stone of a fraction of 5 cm. Thus, for a septic tank 2.5 m deep, you will have to dig a pit 3.1 m deep.



4. The rest of the formwork is done on top of the pillow. The formwork along the walls is one-sided - the second side is the earth.



5. Inserted into the formwork at a height of at least 80 cm from the bottom drain pipe 100 mm in diameter. If it is above freezing of the soil, the pipe must be insulated.
6. A tee is inserted into the wall formwork between the chambers, through which settled water will drain into the drainage chamber. It should be 20 cm below the drain pipe.
7. Concrete can be kneaded both manually in a trough with a chopper, and a concrete mixer. To give the mixture elasticity and frost resistance, you can add a tablespoon of ordinary washing powder to each bucket of water.



8. Concrete mixed with crushed stone and stones is poured into the formwork different sizes, and the mixture itself is bayoneted, removing air bubbles. The pipe and tee are poured so that after the formwork is removed, there is a monolithic wall around them.



9. As soon as the concrete hardens, you can make the top floor. It is most convenient to use corrugated board for formwork. It is laid so that it goes halfway onto the walls of the septic tank - so that when pouring, the roof and walls merge into a monolith.
10. A technical hatch with a diameter of 1 m is made, around which formwork is installed. It is necessary to make two holes above the chambers and insert pipes. In the main chamber there is a pipe with a diameter of 100 mm and a reverse slope for pumping out sludge, which does not reach the bottom by 20 cm. A vacuum release hole is made at the end of such a pipe. Inserted into the second ventilation tube 50 mm in diameter.





11. An overlap with a minimum thickness of 15 cm is poured with the obligatory addition of stone and bayonet. After hardening, the septic tank is covered with waterproofing and can be completely covered with earth, leaving only a technical hatch. So that in winter the septic tank does not freeze through this hatch, it is covered with foam plastic and covered with another lid.

An improved do-it-yourself cesspool is ready to go. After some time, the bottom of the main chamber becomes silted, bacteria develop there, increasing the filtration capabilities of the pillow, and the final cleaning of the drain water takes place in the second chamber.

And how to make a simple cesspool is described step by step in the video: