The device of the drain pit: popular design schemes + analysis of the rules for determining the depth

Nikolay Fedorenko
Checked by a specialist: Nikolay Fedorenko
Author: Tatyana Zakharova
Last update: March 2019

The construction of a local treatment plant allows for the quality processing and filtration of sewage to the state of process water. However, this option of organizing autonomous drainage is expensive.

An alternative solution for suburban or country houses is the arrangement of a drain pit with your own hands. There are several options for homemade cesspools that differ in manufacturing materials and functionality. Which one is preferable? Let's try to figure it out.

The article describes popular drain pit schemes, as well as step-by-step instructions for their construction. Practical recommendations will help you make the right choice and organize the removal of sewage by yourself.

Drain pit - part of an autonomous sewage system

To collect household and household waste, a storage tank is needed, which must be regularly emptied using special equipment. Usually this is a large tank or structure buried in the ground.

The sizes and shapes of the cesspools may vary, but some components must be present in all structures:

  • storage tankthe volume of which meets the needs of the owners of the house;
  • drain inletthrough which sewage flows into the tank;
  • technical hatchnecessary for control and maintenance;
  • ventilation pipethat removes harmful gases to a safe height.

The ventilation device is often neglected, leaving a hole or slot for air to penetrate inside, or even completely plugging the hole. This is wrong: the unpleasant smell of gases at a certain concentration is also dangerous.

Street toilet
There are still street birdhouses, “birdhouses,” which completely replace the country sewerage: they are both a latrine and a store for food waste

Everyone who feels the discomfort of walking in the morning chill has long equipped a full-fledged sewer network. It includes nodes for connecting to the toilet, sinks, bathtub or shower, and a pipeline connecting the points inside the house with a nearby reservoir buried.

The minimum “summer residence” set that allows you to regularly wash and keep the house clean is a toilet + shower + sink in the kitchen. Accordingly, the sewer system inside the building connects plumbing devices.

The outer part of the system is a pipe from the wall of the house to the storage tank. A straight and relatively short pipe (but according to the norms of SNiP not shorter than 5 m) is an ideal scheme for moving wastewater.

Scheme of the device of the country sewerage system
The simplest device diagram of a country sewerage system with a drain pit. A mandatory addition is the arrangement of the road - the entrance for the cesspool truck

Sometimes it is necessary to equip complex communications connecting several hoses, for example, to drain drains from a house, a bathhouse, a garage or a summer kitchen. But in this case, instead of the usual drainage pit, a septic tank is installed, which, in addition to collecting and accumulating, also purifies the water, and then displays it for tertiary treatment in the ground (well, ditch).

Types of cesspools by material

To equip the drain pits, both factory-made blanks and improvised material are used, for example, car tires or red brick left over from building a house.

Consider the design features of different models and find out which of the storage tanks will last longer.

Waterproof masonry

With the advent of ready-made concrete rings, the installation process of which reduced the construction of the pit several times, brick became less and less used. It makes sense to use it in extreme cases, when there is no way to purchase another, more modern material.

Sometimes it remains in large numbers after the construction of the house, and if time permits, it is possible to build a brick cellar.

Brick Drain Pit
The shape of the brick cesspool can be any: from a round, resembling a water well, to a rectangular one - the service life does not depend on the configuration. Typically, brickwork has been without repair for no more than 15-20 years

Brickwork is performed in the traditional way, but first the bottom is prepared. A concrete slab is laid on a sand-gravel pillow, which is fixed in the ground with the help of reinforcement.

The finished slab can be replaced by pouring cement mortar. Concrete slabs can also be useful in the construction of the upper part - the ceiling, to which the technical hatch is attached.

Scheme of a cesspool
One of the options for a brick cesspool. Along with the waterproofing layer, you can use a clay castle, which is a natural protection against penetration to the walls of a cesspool of groundwater (+)

In this way, brick pit device includes the following elements:

  • concrete bottom;
  • perimeter masonry;
  • floor slabs;
  • hatch with a cover;
  • plastic ventilation pipe.

When arranging a tank consisting of relatively small elements, it is important to properly seal so that the effluents do not fall into the adjacent soil. It consists of two stages - waterproofing the inner and outer sides.

Bitumen-based coating mastics, as well as modern penetrating Penetron-type materials, have proven themselves well.

Well from tires

The most unreliable solution, whose service life does not exceed 10 years, is a rake from tires. Automotive rubber is not intended to be used as parts for sewage, so over time it does not withstand the effects of aggressive chemicals and collapses.

In addition, difficulties arise with the sealing of joints between the tires to ensure the sealing of the well.

Tire drain pit
The unreliability of the shaky structure is compensated by arranging the pit from the outside: they make protection from sand-cement backfill, seal the entire structure, use geotextiles and ruberoid

The bottom of the pit is equipped in the traditional way for all drives: they lay a concrete slab or make a cement screed. In the upper part, a flooring is usually built of strong boards and a hole with a lid is left for maintenance - pumping sewage.

A tire drive cannot be large in volume, so get ready for the frequent call of vacuum trucks.

Tire pit
The scheme of the device drain pit from car tires. To increase the interval between visits to the scavengers, a perforated pipe is mounted in the bottom of the pit, through which part of the liquid seeps into the ground (+)

It should be understood that after some period (in some cases, from 3 to 5 years), it will be necessary to disassemble the rubber structure and erect a new well, because tire drain pit can not be repaired.

For this reason, experienced builders recommend installing more durable structures designed for 50 years - for example, drives from concrete billets.

Monolithic concrete tank

The device of a bulk container made of concrete is fundamentally different from the construction of structures from individual finished elements (bricks, blocks, tires). It does not consist in assembly, but in the creation of formwork followed by concrete pouring.

The result of construction work should be a strong, reliable, sealed concrete tank with a service life of at least 50 years.

Formwork device for drain pit
For the formwork using wooden boards left over from construction work, pieces of plywood, timber. Also, reinforcement is required - to strengthen concrete walls and the base

The order of the device drain pit of cast concrete:

  • pit preparation, bottom leveling;
  • reinforcement and concreting of the base;
  • formwork construction;
  • installation of fittings for walls;
  • step-by-step concrete pouring;
  • installation of floor slabs;
  • waterproofing structures;
  • ventilation and hatch device;
  • backfill.

Often, during the construction of the simplest septic tank, a more complex scheme of two chambers is used. Simply put, approximately in the center of the structure, a concrete partition is installed with an overflow hole.

The two-chamber structure partially clarifies the drains, and the use of an additional filtering well allows part of the sewage to be sent directly to the ground.

The device of a concrete septic tank
The scheme of a concrete monolithic structure with two compartments indicating the possible sizes. Both cameras have a message in the form of an overflow pipe installed below the level of the inlet (+)

Feature solid concrete pits is a long construction period and compliance with the standards for the preparation of cement mortar.

Concrete Rack

Prefabricated concrete blocks are prefabricated for several reasons:

  • construction speed - construction takes less time;
  • relative availability - the cost belongs to the category of democratic;
  • durability - subject to the rules of construction, the structure has served for more than 40 years;
  • strength - a well of heavy rings fastened with a lock connection is much stronger than a construction made of tires or bricks.

Concrete rings, as well as other parts for construction (bottom, floor slabs, extensions), can be purchased at the nearest enterprise that produces concrete products.Alternative option - make w / w rings by yourself.

We'll have to rent equipment and hire a team of workers, but installation will take place quickly, in contrast to the creation of a monolithic tank.

Concrete ring drain pit arrangement
The height of the cesspool of concrete blocks (therefore, the volume of the tank) depends on the amount of sewage. The most popular designs consist of 2 or 3 rings and are designed to serve families of 2-4 people

In addition to concrete workpieces, backfilling for the base (sand and gravel) is required, joint sealing waterproofing and external sealing of the finished structure. To give the structure strength and stability, dry cement is added to the backfill soil.

Concrete Ring Pit
Scheme of a drain hole made of concrete rings. This option has a perforated bottom, that is, it is able to pass part of the effluent out. Such a pit arrangement is impossible if clay soils rather than sandy soils prevail in the garden (+)

Despite the existence of schemes of cesspools without a bottom, single-chamber tanks are recommended to be sealed, since insufficiently purified water pollutes the soil and fertile soil layer.

Factory-made plastic container

If you want to install a drain hole in one day, pay attention to the finished models of modified plastic, presented on the market of autonomous sewage by well-known companies.

They differ in shape and size, but all have sufficient strength so as not to collapse under ground pressure or from the movement of groundwater.

The device of the drain pit from a plastic container
The advantages of plastic models are in strength, reinforced with stiffeners, and absolute tightness. In a container made of polyethylene, unlike prefabricated analogues, there are no joints and seams, therefore there is no risk of depressurization

Installation of a plastic container is carried out according to a simple scheme: they dig a pit, strengthen the bottom (with unreliable soil or high groundwater), install a tank, connect it to the pipe and fill it up.

The process of pumping sewage waste occurs in the usual way - with the help of sewers.

Read more about choosing and installing a plastic tank in this article.

Overview of Popular Schemes

Despite the material of manufacture, sewer structures can have a different design. The difference concerns, to a greater extent, the number of cameras - from one to three. Consider the schemes that are most suitable for providing private homes with autonomous sewer.

Separate storage capacity

A rake from one sealed chamber is the easiest option. It does not pollute the environment, therefore, it is safe and environmentally friendly. Such a pit takes up a minimum of space, and since it is underground, it does not interfere with growing flowers or breaking beds nearby.

The restrictions relate to the planting of trees, which with their roots can depressurize the sewer system.

The scheme of the simplest drain pit
Scheme of the simplest single-chamber cesspool. It is necessary to ensure that the wastewater does not rise above the level of the sewer pipe, and call the sewage system on time

A single-chamber drive is relevant for those who rarely use the sewer system, that is, rarely visits the cottage. There is another option - if a lonely person lives in the house, and the sewer system consists of a minimum of active points of use (toilet, shower, sink).

When installing the tank, it must be remembered that it is not filled to the very top, but to the level of the pipe inlet, therefore it is only used for 2/3 of the volume. A simple drive requires regular pumping, and for this it is necessary to prepare a convenient access road for sewage trucks and it is better to conclude a contract for ongoing maintenance.

Draining pit without bottom

Single Drive Option - filter bottom pit. The main purpose of the filter is to pass part of the effluent directly into the ground in order to reduce the load on the structure and reduce the number of specialist calls for pumping waste.

The design of the bottom of the tank is different from the blank bottom of the sealed chamber. It can be a construction from concrete billets, a brick well or a plastic container.

Diagram of a drain pit without a bottom
Scheme of a cesspool with perforated walls and a filtering bottom. The filter is a thick sand and gravel cushion, which must be updated over time

In soils with low throughput, for example, in plastic sandy loams, it is advisable to arrange additional perforation of the walls. For this, small holes are formed after about 10 - 15 cm.

They are placed along the entire height of the soil filter in a checkerboard pattern. Such methods increase the filtration area, as a result, the recycling process is accelerated.

Two important conditions for a filtering device:

  • sandy or sandy loamy soil - loose, with a high degree of water permeability;
  • low level of water horizons.

Dense clay soils, hard sandy loam, loam of any consistency, simply will not absorb water, so the perforation device is useless.

This scheme is more suitable for construction of filter wells, which are the second or third compartment and are installed after the drive. The quality of post-treatment in the soil of partially clarified water is much higher than that of non-settled sewage from the first storage cell.

Pumping waste from a pit without a bottom is carried out a little less often than from a normal pit. If the filter is clogged, the pumping mode is the same.

Two-chamber septic tank made of concrete rings

A complicated version of the drain pit is a double tank.

It can have a different design:

  • concrete tank, divided into 2 parts by a partition;
  • 2 wells connected by overflow pipe.

Despite some differences in design, the goals of building two-chamber models are the same - to separate the waste by degree of pollution.In the first section, which is a full-fledged storage tank, waste treatment by anaerobes begins, as a result of which a solid precipitate and a turbid liquid are formed.

In the second, the wastewater is clarified even more, the sludge is much less.

Two-chamber septic tank
A device variant of a two-chamber septic tank. The second tank is a filtering well that receives drains from the first chamber and sends them to the ground for further treatment (+)

If the second tank is equipped with a compressor, then the cleaning will be more effective, since the processing will also be carried out by aerobic microorganisms. Two-chamber models, in fact, are no longer just drives, but septic tanks that can partially clean sewer drains.

Brief process construction of a two-chamber septic tank of concrete rings presents the following photo selection:

How to determine the depth of the cesspool?

The dimensions of the drain pit, including the depth, depend on the volume of wastewater. First, we calculate the total number of effluents per day, multiply by 10-14 days (depending on the frequency of pumping), we find the desired working volume. Worker means only to the level of the pipe insert.

If you need a working volume of 4 m³, then add another 1/3 and get the volume of the tank - 6 m³. Knowing the volume, we calculate how much concrete rings are needed or what is the length / width / height of a monolithic structure.

When constructing a foundation pit, add 0.3 m to level the base and arrange a sand and gravel cushion. We calculate the depth of the drainage pit so that during installation part of the neck (about 0.2 m) is visible above the ground.

A small ledge is insurance against spring flood. At the risk of seasonal flooding, the neck can be raised by 0.5 m.

Cesspool drawing
It is better to prepare a drawing indicating the depth and other sizes in advance, and in the future, the calculations made should be strictly adhered to. When buying ready-made containers, installation and installation instructions are included (+)

A little different calculation of the depth of the pit without a bottom. Excavation pit with perforation deeper than the sealed analogue due to the installation of a meter sand and gravel filter. In order not to be mistaken with the calculations, we simply add the thickness of the filter pad to the height of the structure.

When calculating, do not forget about the location of water horizons - from the base of the cesspool to the upper aquifer should be at least 1 m.

Conclusions and useful video on the topic

The rules for the construction of storage tanks and septic tanks are very similar, therefore, we recommend viewing the following interesting thematic material.

Construction of a brick pit with overflow in high groundwater conditions:

Useful information on the construction of a two-chamber structure:

Details of the construction of septic tanks:

Having become acquainted with the structural features and characteristics of cesspools, you can independently equip the sewer system in the suburban area. If you have difficulty in plotting or calculating the depth, we recommend that you contact experienced engineers.

Do you have practical skills in constructing a drain pit in a personal plot? Share your knowledge, ask questions on the topic and participate in discussions. The comment form is located below.

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Visitors Comments
  1. Ivan Perov

    In my village there is a cesspool of 2 concrete rings. But the problem was that we did not deeply lay and did not heat the plastic pipe (drain). Since our winters are cold, she burst. I had to change, of course, an unpleasant procedure. By the next winter, they made insulation, three seasons passed until it froze. The neighbor has cast-iron pipes, they are better, but, alas, we did not have them. The neighbor does not have such problems.

  2. First of all, you need to decide on a place under the drain hole. It should be away from the foundation and well or water well. And you also need to immediately decide how the car will drive up to pump out sewage. In addition, you need to know the volume of the planned pit, it is also necessary to equip a technical hatch. And then it all depends on your financial capabilities: it may be a brick pit with a concrete floor, or it may be a well assembled from concrete rings.

  3. Pavel

    Interested in the design of old car tires. The price, compared to the rest, is just penny. Yes, and you can do it yourself. And what joints between them usually seal?

    • Expert
      Nikolay Fedorenko

      Hello. detailed instructions for the construction of such a design can be found in this article on our website. It should be noted that with a high level of groundwater, such a design is not advisable. In addition, cleaning such a pit is difficult.