What does septic mean? How septic tanks work: design and types of treatment systems

The septic tank prevents harmful substances into the soil

Waste disposal in a private or country house has its own characteristics. Connect frequently central system unreal. Then a sewer septic tank comes to the rescue. This is an autonomous system that allows not only to accumulate wastewater, but also to dispose of it. There are many types of septic tanks, and you can choose the best option for any home.

A septic tank is considered closed installation, which is used to collect and dispose of wastewater. A similar system is used to create an autonomous civilization in a private or country house. The design of a septic tank can have different options. You can purchase a ready-made septic tank or make it yourself.


The principle of operation of a septic tank can be seen in the illustration presented.

Criteria by which septic tanks differ:

  • Principle of operation;
  • Material for equipment;
  • Location option;
  • Form.

Materials used for a septic tank include plastic, metal, concrete or brick. The main criterion by which septic tanks are divided is the type of work. Some structures are used only for collecting waste. They differ from cesspools in their tightness. Models with mechanical and biological wastewater treatment are also presented.

The shape of septic tanks can be horizontal or vertical. Depending on the location, the structures can be above ground or underground.

The easiest way is to organize an individual sewer system with a sealed septic tank only for waste collection. But what makes it practical is the design with a wastewater treatment function. Can be installed combined option, where several compartments are provided at once. Each camera performs its own functions.

In the first compartment, wastewater accumulates and settles. Ventilation is provided to remove gases. Then the wastewater moves to the next chamber, where bacterial purification occurs. The final filtration takes place in the last compartment.

Determining why a septic tank is needed on the site

Often a private house does not have a central sewer system. The owners will equip an autonomous option. The central figure in it is the septic tank.

The principle of operation of a septic tank:

  1. At the first stage, wastewater is collected. For this purpose, a prefabricated well is provided. It is completely sealed. Inside, the heavy parts settle at the bottom, and the light ones remain on top. Then the liquid is sent to the second compartment.
  2. At the second stage, filtering occurs. It can pass through a well or a field.

Anaerobic bacteria work in the collection tank without access to oxygen, because the well compartment is sealed. During the work of microorganisms, methane is released. It is removed using a special tube. Its height must exceed the height of the roof.


The septic tank on the site can be located almost anywhere

After the first compartment, the wastewater is only half cleaned. Final cleaning takes place in the following containers.

The second compartment has no bottom. Instead, a cushion of crushed stone with sand is used. Its thickness is in the range of 30-60 cm. It all depends on the type of soil. For clay soil, a maximum thickness is provided.

Types of autonomous sewerage septic tanks for a summer residence

The purpose of using a septic tank is clear - waste collection and processing. It is installed when individual sewerage equipment is required. There are different types of septic tanks, the choice is quite wide.

Types of septic tanks:

  1. Cumulative. The design has a simple operating principle. This is the most cheap option. The wastewater is not recycled. Periodically, waste products are pumped out using a sewer truck. This option is suitable for a dacha where the owners spend only the warm season.
  2. Septic tanks. In addition to collecting wastewater, it is settled. As a result, 70% of waste can be recycled. Next, the wastewater must undergo additional filtration in order to be completely cleaned. The devices must be periodically cleaned of sludge.
  3. Deep cleaning design. Thanks to this septic tank, waste can be purified by 95%. The cost of the device is high, but the quality of work will also please you. You can remove the sludge yourself without the help of specialists. It doesn't take much effort to install the structure.

Before purchasing a septic tank, you should consult with experts about the advisability of choosing a particular model.

Septic tank sizes may vary. The device is selected individually depending on the number of residents in the house. In addition, when choosing a design, its performance is taken into account. It is measured by the amount of waste processed per day. You can make a septic tank yourself. At the same time, it is important to comply with technology, sanitary standards and rules.

Antiseptics and septics - what are these terms in medicine?

The concept of “septic tank” means “rotting”, if you translate the word from Latin. But now the term indicates the presence of harmful bacteria. The concept is considered medical, but it can also be found in other areas of life. Septic tank is considered the antonym of antiseptic.

Antiseptics includes a complex of disinfecting actions in the field of surgery. But now the designation of the concept has a wider range of uses. Now antiseptics refers to actions that are aimed at combating pathogenic microorganisms in wounds, organs, tissues and the body.


After installing the septic tank, only its upper part remains visible

In medicine you can come across the concept of “asepsis”. It refers to a set of measures to prevent bacterial infection.

Antiseptic drugs are found in different areas of life. They are used in construction and everyday life. Antiseptics are believed to kill bacteria. This is often noted in various advertisements. Chamomile decoction, toilet bowl cleaner, and penicillin may also have antiseptic properties. But the scope is different.

There is no need to confuse the names “septic tank” and “septol”. The term is taken from medicine and means disinfection. But in the sewer system, the device is used to collect and process wastewater. In this case, the waste goes through several stages of purification, and in the end an absolutely clean liquid can be obtained.

If the dacha or Vacation home does not have a connection to the central sewerage system, the question arises of what a septic tank is and how to make it and install it on personal plot. Many homeowners would like to arrange it themselves. After all, wastewater disposal using a conventional cesspool is not effective enough and has a number of disadvantages.

You need to understand what a septic tank is and how it works. A septic tank is a small sewage system consisting of filters, a storage tank and a pipeline. A septic tank is a cleaning device Wastewater and their subsequent filtering. After this, the water becomes suitable for discharge into the soil or into a nearby body of water.

Depending on the design, septic tanks for sewerage in a private home differ in the method of cleaning incoming wastewater, productivity, durability, etc. An important indicator is the frequency of cleaning the structure itself using sewage equipment.


The storage septic tank is quite simple. In this design, wastewater flows from separate sewer pipes into a collector, and from there into a special container. Here, biological suspensions settle, which subsequently decompose under the influence of special microorganisms. The main volume of waste liquid in such a system seeps into the ground, which is a natural additional filter for water purification.

The most effective is a 3-chamber sewer septic tank with natural wastewater treatment. Cleaning tanks in such a treatment system can be arranged in different ways. The material for the manufacture of storage containers can be:

  • plastic;
  • stainless steel;

How does a septic tank work?

The principle of operation of a septic tank modern model, consisting of a pipeline and a treatment system, allows you to almost completely purify wastewater and discharge it into the ground without causing harm to the environment.

From the sewer pipes located in the house, used water flows into the 1st tank of the septic tank. Insoluble waste particles contained in the water sink to the bottom of the container. Additionally, under the influence of the fermentation reaction, organic substances dissolved in water are bound and, thus, wastewater undergoes primary treatment.

Then the water containing small impurities is poured by gravity into the 2nd tank. The purification process here takes place in the same way as in the 1st tank, taking into account the fact that the amount of impurities in the water is less, and therefore the biological purification process takes longer.

After repeated purification and clarification, the wastewater is poured into the 3rd tank. If it is a sealed container, the water after settling for drainage pipes moves to the filtration area of ​​the earth. Distributed evenly over it, the wastewater passes through a specially equipped bed of crushed stone, sand or other bulk material. The purified water is then absorbed into the soil. If used as a 3rd tank drainage well, a cushion made of bulk material is placed in the bottom of a well, the walls of which can be lined with brick.

After clarification and settling, the water flows into the aeration field. Here it is filtered as it percolates through the soil. Additional cleaning is provided by bacteria and other microorganisms that live in upper layers soil.

Preliminary calculations

The defining moment when arranging a septic tank with your own hands is the correct calculation of the required dimensions of this device and compliance with technological requirements during its construction.


The key factor in determining the required size of septic tank treatment tanks is the volume of wastewater generated when using plumbing fixtures within 3 days.

According to average statistics, when 1 person uses plumbing, approximately 600 liters of wastewater are generated within 3 days. By multiplying this number by the number of household members, and adding a little for insurance, you can get the value necessary to calculate the volume of the septic tank. It turns out that the required volume of a septic tank for a family of 3 people is about 2 m³. If for some reason it is difficult to install a treatment system of sufficient volume, the cleaning efficiency can be increased using special aerators - systems that saturate wastewater with oxygen.

Aeration septic tank

Aeration septic tank, what is it? At its core, this is a conventional 2- or 3-chamber wastewater sedimentation tank, the efficiency of which is increased through the use of aerators. In an aerobic septic tank, water passes through 2 or 3 containers, in which hard particles gradually settle. In the last chamber, the wastewater is purified using oxygen. The water supplied to the soil is almost pure and suitable for irrigation. It is possible to discharge such water into a nearby body of running water.


The disadvantages of such a septic tank include the need to purchase an aeration system, as well as installing power supply circuits for the aerator. The electrical power consumed by the aerator is small, but like anything electrical device, the aerator requires periodic inspection and maintenance.

Manufacturing of sewer system

A concrete tank for a septic tank can be made from concrete rings or in the form of a well or pit lined with concrete from the inside. This well or pit is usually divided by partitions into 2 or 3 compartments. In addition, it is necessary to equip an aeration section for secondary filtration of incoming wastewater.

A septic tank made of concrete rings is installed to a depth of no more than 4 m. The diameter of the concrete ring is from 70 to 200 cm. The ring weighs about 0.6 tons. To deliver concrete rings to the local area, a truck is required. The ring can be rolled along the section to the site where the septic tank is being built.


If it is impossible to use heavy construction equipment, the installation of a drain well can be done by gradually immersing a concrete ring into the ground. Having installed the ring in the selected area, you need to gradually remove the soil inside the ring, while the ring will be lowered into the well. Gradually, the upper edge of the concrete ring will be level with the upper edge of the soil. Now you need to install the next ring on top of it. Align it and secure it using special spacers or reinforcement welded from the inside.

Once the required depth of the well is reached, a concrete bottom must be installed inside the rings. Concrete mortar The joints between the rings also need to be sealed. After that, dividing partitions are made and installed inside the drain well. You can also dig a pit required size, build formwork inside it and pour concrete. Then the formwork is removed.

Necessary components for a septic tank


To set up an effective local sewage system - a septic tank, you will need:

  • tanks made of plastic or stainless steel;
  • sewer pipes through which wastewater will flow;
  • hatches through which free access to each chamber will be provided;
  • pipes for arranging ventilation risers that serve to remove gases resulting from fermentation of wastewater;
  • a pump of a special device for removing purified water from the last chamber.

When arranging a septic tank without using ready-made tanks, you will need the following materials:

  • concrete mortar or concrete rings;
  • concrete plates;
  • boards for assembling formwork;
  • geotextiles for sealing;
  • crushed stone or other bulk materials for arranging the filter layer;
  • steel cable or tape.

To build a septic tank with your own hands, you need to prepare the following tools and devices:

  • concrete mixing tank;
  • construction mixer or electric drill with a whisk attachment;
  • measuring container for measuring concrete mortar components;
  • construction tape;
  • shovels - shovel and bayonet;
  • construction scissors and/or a sharp knife;
  • plumb and level;
  • welding machine for welding pipes;
  • saw;
  • work clothes;
  • rags.

Construction of a septic tank from a finished tank

It is also necessary to dig a pit for a septic tank made from a Eurocube or other ready-made tank. The settling chambers are pre-connected to each other by overflows for the free passage of water. Then the entire structure is placed in the finished pit. Additionally, it is necessary to arrange the passage of water from the last container to the aeration area.

It is advisable to purchase chambers for a septic tank with corrugated walls. In this case, the required wall thickness should be about 0.7 cm.

To install the tank, you need to dig a pit. Its value is determined by the size of the purchased container. On each side you need to add another 20-25 cm.

When the hole is ready, you need to place a concrete slab on the bottom. Then the tank must be filled with water and placed at the bottom of the pit. The septic tank container is attached to the concrete slab with a special cable or steel tape. This will prevent the reservoir from being squeezed out onto the soil surface. You can pour a cement-sand mixture (ratio 1 x 10) into the hole or pour a solution prepared according to the usual recipe.

Septic tank from eurocubes

Eurocube is a special cube-shaped container designed for storing and/or transporting liquid and bulk materials. Since for the manufacture of such containers enough reliable material, they can be successfully used when installing septic tanks.


It is necessary to prepare a pit for a septic tank made from Eurocubes in a similar way. A concrete layer with a thickness of at least 20 cm is poured onto the bottom. Then a Eurocube is installed in the hole. The inlet and outlet pipes are mounted to it. Then water is poured in. The lid closes hermetically. After this, the free space in the pit is filled with concrete solution.

Septic well

A septic tank in the form of a well is dug in the same way as a cesspool. Then it is connected to the filter container or to the filtration field.

The filter tank is constructed of reinforced concrete rings. A cushion of bulk material is placed at the bottom to filter wastewater.

It is necessary to arrange outlet openings in the walls of the filter container. total area These holes should be 10% of the area of ​​the walls of the filter container. The average diameter of each hole is from 4 to 6 cm. A filter layer of bulk materials must be poured around the walls of the container.

Filtration section

To equip the filtration section, it is necessary to lay a distribution pipeline from the septic tank. Pipes with a diameter of 10 cm are laid with a slight slope.


An irrigation system made of pipes with a diameter of 10 cm is connected to the distribution pipeline. At the junction of the distribution and irrigation pipes, inspection wells are installed, or pipes are brought out to a height of up to 40 cm above the soil level.

Irrigation pipes are laid at least 1 m above the location of groundwater. In this case, the pipes should pass 80-120 cm below the soil freezing level. It is necessary to drill small holes (5 mm in diameter) in the irrigation pipes, directed into the depth of the soil at an angle of 60°. They are placed in a checkerboard pattern every 5 cm.

Before installing the pipes, it is necessary to pour and level the bulk materials for the filter. Required thickness layer - 2 cm, width - 2.5 cm. Pipes must be immersed in bulk material to 0.5 diameter.

The ends of the irrigation pipes are equipped with risers, which must be placed 2 m above the soil level. The required diameter of the riser is 10 cm. Air will pass through the risers, providing aerobic treatment of wastewater.

Rules for installing a septic tank

Septic tank sewerage requires compliance technical standards during installation. A sealed storage septic tank without an aeration section can be installed at a distance of at least 5 m from the house and other buildings. When creating a septic tank from 2 or 3 chambers, you should remember that each subsequent tank must be located lower than the previous tank. Below everything is a filtration field, when installing it, the septic tank must be removed from the house or open reservoir at least 30 m. In this case, the septic tank must be located at a distance of at least 50 m from the source of drinking or industrial water supply.

To equip each settling tank, 1.5-3 m² of area is required. The average filter field size for a family of 4 people is 30 m².

Geotextiles for sealing a septic tank can only be used of the thermally bonded type. Needle-punched geotextiles will quickly become overgrown with silt and become unusable.

There should be no buildings or vegetation on top of the filtration field. It is only allowed to arrange a flower bed or lawn, on which it is advisable to plant only lawn grass and small flower crops.

Improvement of a country house or dacha in the absence of centralized sewerage networks nearby is carried out with the help of autonomous systems, one of the main elements of which is a septic tank. It is into this container, consisting of one or more chambers, that wastewater is collected and subsequently purified. The more complex the design of the septic tank, the more effective the purification of the sewage that enters it. When choosing finished design treatment facility takes into account the daily volume of waste. On this value is influenced by the number of residents permanently residing in the house, as well as the availability and intensity of use of plumbing equipment. Any type of septic tank must provide a sufficient degree of wastewater treatment for its further disposal into the ground without the risk of contamination. If desired, the home owner can pump out the septic tank by calling a sewer truck for this purpose.

The video clearly shows the principle of operation of the Topol septic tank as an example:

How is wastewater in a septic tank treated?

Wastewater, entering the first chamber of the treatment plant through the sewer drain pipe, breaks down into separate fractions. Particulate matter big size fall to the bottom, and smaller suspensions along with water fall into the second chamber, where they are “attacked” by special an aerobic bacteria. Fermentation processes are active in both chambers, resulting in the release of methane gas.

The entrances to the individual compartments of the septic tank are closed with a shutter formed by the flow of water, which prevents the spread of unpleasant odors around the treatment plant. The third chamber is equipped with a special removable filter that catches leaked contaminants from the first two compartments. Here, aerobic bacteria, whose vital activity is possible in the presence of oxygen, enter into the struggle for clarification of wastewater. This is exactly how we can describe the operating principle of septic tanks produced by both Russian and foreign manufacturers.

Ready-made models of septic tanks produced by Russian and foreign manufacturers are lowered into a prepared pit. Effluent purified as a result of three-stage treatment enters the filtration field and goes into the ground

Important! As a result of multi-stage treatment of sewage waste, it is effectively purified. The treatment plant itself can function longer without maintenance and pumping with special equipment. The sanitary condition of the site depends on how the septic tank works. At high-quality cleaning never appear near structures unpleasant odors, having a specific aroma of operating sewerage.

Advantages of using septic tanks

Why use this particular treatment plant? Here's why:

  • the possibility of the maximum possible purification of sewage water from harmful substances;
  • operation of structures in any climatic conditions, including low temperatures in winter;
  • no need for frequent pumping;
  • long service life of the treatment plant;
  • independence of some septic tank models from power supply.

Principles for creating a homemade septic tank

Septic tanks are presented on the Russian market in large assortment. Ready-made tanks, oriented in a horizontal or vertical position, are easily installed in a pre-dug pit. These containers can be made of durable materials that can withstand aggressive environments. Typically, manufacturers produce products from plastic and fiberglass, but there are also models made from metal and reinforced concrete structures.

The cost of ready-made septic tanks is quite high, so many owners of private houses, cottages, and summer cottages are engaged in constructing single-chamber or double-chamber septic tanks with their own hands. In this case, a trench is dug manually or with the help of a tractor, into which concrete rings are lowered and connected with an overflow pipe. As a rule, such installation of a treatment plant requires physical effort, but not financial effort. This is what an approximate diagram of the device looks like homemade septic tank, built from three to six concrete rings.

The first well (sump) must have a concrete bottom, which does not allow dangerous bacteria to penetrate into the soil. In the second well, the bottom base is covered with layers of sand and crushed stone, necessary for filtering the wastewater coming in purified form from the sump.

Schematic layout of a three-chamber septic tank made of concrete rings in the form of three wells. In the first and second wells, liquid waste is purified, and in the third, it is discharged into the ground

Important! To ensure waterproofing of the structure of a homemade septic tank, the seams between the rings are coated cement mortar and are additionally treated with special water-repellent mixtures.

Knowing how a typical septic tank is structured and by what principle its functioning is organized, you can always build such a structure with your own hands from available materials.










When building a private house located far from the central sewer system, there is a need to build an autonomous system. A suitable option there will be a treatment facility here and the more efficiently the septic tank is installed, the more convenient it will be for the residents of the house. How a septic tank should be equipped, the principle of operation and its design are in our article.

The main components of a septic tank for a country house

Scheme of the device and principle of operation of the septic tank

When considering the design and principle of operation of the sump, it turns out that all treatment facilities have much in common.

Most autonomous sewage systems are combined containers for the gradual purification of waste and the production of sediment in the form of insoluble particles of various inclusions.

The tanks are made from various materials(reinforced concrete rings, car tires, bricks, flat slate). They are also made in different configurations.

Principle of operation

The operating principle of a septic tank equipped according to all the rules is complex circuit, as a result of which, Negative influence on the ground and environment is reduced to a minimum. According to the traditional scheme, a septic tank is a treatment facility, and it looks like a device of two or three chambers. The first container is a storage facility for waste directly from the sewer line.

This is where the mixture decomposes. In the chamber, the wastewater breaks down under the action of bacteria into a sludgy substance and settled water.

IMPORTANT! The first tank should be of such a volume that it is enough for use for three days, during which the mass decomposes.

After the water has settled and purified a little, it flows into the second chamber - the filtration well. If the first container is made hermetically according to SNiP, then the second one must be made with a drainage bottom (crushed stone, gravel or sand). Water passes through the drainage, is filtered and absorbed into the ground, thereby not polluting it.

Scheme of a simple septic tank with soil purification drains

Advantages and disadvantages of septic tanks

Depending on how the septic tank is designed, the family’s living conditions will radically improve, and this will be the main advantage of such a treatment facility. Besides, it has many other advantages. Let's look at them in more detail:

    Long service life.

    On local area no unpleasant odors.

    There is no need to order a sewer truck often.

    The risks of soil contamination are significantly reduced.

    Easy and reliable installation. When constructing them, ready-made septic tanks “Termite storage tanks” or “Tank” are also used - stations for complete decomposition of waste.

The disadvantages of settling tanks include the large volume earthworks when installing and the high cost of polymer septic tanks.

Septic tank or cesspool: nuances of choice

IN modern house For domestic needs, a large volume of water is consumed, which requires disposal. When installing a sewerage system, you first have to choose between simple cesspool and a septic tank. What problems do you face when choosing? Let's look at these nuances in more detail:

Disposal rules. A cesspool is a simple storage facility for waste, and it is stored there until the storage facility overflows.

To clean the cesspool, you will need regular services of a sewer truck.

The larger the family composition and water distribution devices, the greater the water consumption. The design of the septic tank allows it to be used not for storage, but for waste treatment, while 70–80% of wastewater is recycled.

Number of tanks. A cesspool is a single storage facility - a classic septic tank includes two or three chambers.

Service. You need to pump out the contents from the pit as it fills. The septic tank needs to be cleaned much less frequently, no more than once a year.

Frequency of use. If a treatment plant is needed at a dacha where there is seasonal residence, then there is probably no point in installing a larger and more expensive installation. financially- septic tank. A cesspool will be enough.

On our website you can find contacts construction companies who offer design and installation services for sewerage and water supply. You can communicate directly with representatives by visiting the “Low-Rise Country” exhibition of houses.

Septic tanks with soil post-treatment of domestic wastewater

The operation of a local treatment plant depends on the conditions for processing household waste. In this regard, septic tanks can be divided into two types: with ground filtration; with complete biological purification.

After biotreatment, water can be drained into a drainage well

Let's take a closer look at what the difference between them is.

Wastewater treatment plants with soil treatment

The operation of a septic tank with natural filtration is based on gravity. It is well known that any household waste consists of 90-95% water.

The remaining five percent are impurities that, after settling, settle to the bottom of the mixture. Septic tanks consisting of two or three chambers operate on this principle.

In the first case, waste filtration occurs in the second chamber through a crushed stone layer, and in another option, final purification through the soil occurs in a third container or on a specially created filtration field (if the groundwater is high).

Septic tanks with complete biological purification

Such methods complete cleaning allow you to achieve the greatest effect, since they are based on the breakdown of substances under the influence of biological enzymes.

Waste processing in such a treatment plant directly depends on the active work of microorganisms. In this regard, constant monitoring of the process is necessary to prevent the death of living bacteria.

Design and preparatory activities

The main requests for the installation of septic tanks are indicated in SNiP ( building codes and rules). Before starting the installation of a treatment plant, it is necessary to coordinate the project with the sanitary and epidemiological station (SES), otherwise the costs may be in vain.

Standards governing the placement of a septic tank on the site

When developing a project for installing a septic tank, first of all you need to take into account the requirements of SNiP and SES, and they inform about the following:

    The shortest distance to the building is 5 m.

    The distance to the nearest water intake (well, borehole) is 50 m.

    Distance to running water (river, stream) – 10 m.

    The interval to a source with standing water is 30 m.

To competently draw up a project for a septic tank, you need to imagine the prices for installation work, and also know the approximate prices of materials. In addition to this cost, one must take into account the cost of earthworks, which are inevitable for such a treatment facility.

Preparatory work

Before you begin installing the septic tank, you need to make preparations. It involves earthworks and calculation of parameters that affect right choice location and efficiency of the treatment plant.

Preparatory work includes:

    Analysis of the soil structure and topography of the planned site for a septic tank.

    Checking the depth of groundwater. The depth of the installation, as well as the filtration method, depend on this parameter.

When groundwater is high, the design of a volatile septic tank with a drainage pump is most often used.

    Preparing the site for the future septic tank. (Cleaning the area from foreign objects).

    Marking.

    Digging a hole for a structure and trenches for sewer pipes.

After the pit has been dug with dimensions for installation, installation can begin.

Let's consider what difficulties may arise when installing a finished septic tank. First, you need to select a reliable, competent installation company that will install the treatment facility.

Secondly, take into account what material the septic tank is made of - propylene or polyethylene, and what the thickness of the walls is. Thirdly, it is necessary to inquire not only about the price of the equipment and the cost of installation, but also the cost of maintaining the service (the cost of pumping out).

It is advisable to purchase septic tanks from well-known brands, since in this case you can hope that both spare parts and a service company are available in the given region.

To determine the size of the septic tank, you need to take into account, first of all, the number of water taps installed in the house and the one-time discharge of water.

If a small number of people live in the house, then you can consider the option of a small septic tank of the “Kid” type

According to statistics, in our country water consumption per person is calculated at 250 liters per day. But if someone in the family likes to take baths often or does frequent laundry, then this factor also needs to be taken into account when choosing the volume of the septic tank.

In order for the septic tank to serve for a long time and properly, it is necessary to regularly perform preventive inspections. You should also not allow plastic bags, garbage, chemicals, medications, especially antibiotics (they are killers of living microorganisms in a septic tank).

How is wastewater cleaned in a septic tank?

Used for filtering wastewater different schemes cleaning.

Traditional scheme

A classic septic tank is a three-chamber tank. The first two tanks are sealed, and anaerobic (without air access) decomposition of wastewater occurs in them.

Purified, the water gradually flows through overflow pipes into the third - filtration well, in which it passes through a layer of crushed stone and is absorbed into the ground.

ON A NOTE! Since gas is released during the decomposition of organic substances, the settling chambers are equipped with ventilation pipes.

Scheme with a filtration platform

This method is used in cases of high groundwater levels. In this septic tank, the substance also decomposes into smaller fractions, resulting in a sludgy mixture.

But the purified water does not go into the well, but is forcibly pumped out by pumps to the filtration field, which are trenches dug at the top, covered with rubble.

Using a biofilter to filter household waste

A simple biofilter is a reservoir filled with drainage material. Such a filter can be plastic “ruffs”, expanded clay, or crushed stone. But the main condition for successful cleaning here is a large area, since such an area is necessary for the settlement of colonies of microorganisms.

And with this method, wastewater treatment occurs up to 95% instead of 85% in the previous septic tank. Here, pre-purified water enters the biofilter from above, passes through drainage, and simultaneously undergoes mechanical and biological treatment.

Video description

Forced aeration

If a septic tank is equipped with an aeration chamber, it turns from a traditional settling tank into a biological treatment unit. Such a station is adapted to provide the most high quality filtration, therefore such a treatment facility does not need either a well or a filtration site.

Basically, purification here takes place in an aeration tank. The symbiosis of aerobic bacteria effectively decomposes organic matter by dividing complex compounds into simple ones. This septic tank does not need to be cleaned using a sewer machine: they are provided with additional fecal pumps for pumping out sludge.

Cleaning must be done at least once a quarter, otherwise the pump may silt up, stop working, and the station will fail.

Video description

See the video about a septic tank with a biofilter:

Conclusion

Thus, the operating principle of the treatment plant is simple. Septic tanks use natural wastewater treatment processes that occur in nature. Because of competent design installations, septic tanks effectively filter water, and therefore their use protects the soil from pollution and is environmentally safe.


It’s rare that a suburban village or partnership, even near Moscow, can boast of having a main water supply and sewerage system; in general, the owners of suburban real estate have to acquire their own amenities. And in order not to pollute the environment, including the aquifer, with waste from their own vital activity, wastewater treatment systems have long outgrown the simplest cesspools, turning into more advanced structures.

There are a lot of different treatment plants and stations on sale for treating wastewater from mechanical impurities, but despite all their effectiveness significant drawback is a solid price. Therefore, for many private owners the best option homemade devices are becoming well-deservedly popular among FORUMHOUSE craftsmen. Let's consider what a septic tank is, existing sanitary standards, parameters for choosing systems and the most popular varieties.

  • Septic tank operation diagram
  • How to choose a septic tank
  • Construction of a septic tank made of concrete rings
  • Features of monolithic reinforced concrete septic tanks
  • Plastic septic tanks from Eurocubes

Septic tank operation diagram

A septic tank is one of the elements of a complex autonomous (individual) domestic wastewater treatment system designed for collecting, settling and purifying wastewater. Accumulation and sedimentation occurs in a sealed container (when there are several chambers) or containers; from the settling tanks, the wastewater flows into a filtration well or onto soil filtration fields (underground, aboveground). The legislation prohibits the discharge of even settled and treated wastewater from a septic tank into open areas land. The system necessarily includes inspection/cleaning wells and ventilation risers, fan boner brought to the roof level to prevent the possibility of characteristic odors. Septic tanks are periodically cleared of sediment by a sewage disposal machine; if the volume of the septic tank is correctly selected, this procedure, even if you live permanently in the house, is required no more than once a year, or even several years.

Sanitary and building codes and standards governing the location, design and construction of septic tanks

Until recently, the main regulatory documents concerning septic tanks and biological protection stations were SNiPs and SanPiNs developed at the end of the last century and the beginning of this one:

  • SNiP No. 2.04.03-85 (recommendatory), SP 32.13330.2012 (current standard) - parameters for organizing external sewer networks and structures.
  • SNiP 2.04.04-84 and SNiP 2.04.01-85 - parameters for organizing internal and external water supply (outside the city, water supply is most often from a well and a well, and some provisions intersect with the rules for organizing septic tanks).
  • SanPiN 2.1.5.980-00 – protection of surface waters.
  • SanPiN 2.2.1/2.1.1.1200-03 – septic tanks are classified as environmentally hazardous objects; this set of rules regulates the creation of protective zones around them.

Adopted last year new standard organizations autonomous sewerage with septic tanks and soil (underground) filtration of wastewater - STO NOSTROY 2.17.176-2015. Now this is the main document that contains the design and installation rules, as well as the requirements for the results of the work.

For location treatment facilities The following rules apply to other objects on the site:

  • There is 5 meters between the septic tank and the house.
  • Between the septic tank and the water intake (well, borehole) - at least 20 meters, if there is no connection between the aquifer layer and the filter field through soil with high filtering capacity, from 50 to 80 meters if the segment has loamy, sandy or sandy loam soils.
  • Between the septic tank and the side of the road - 5 meters.
  • Between the septic tank and the border of the site - 4 meters.
  • Between the septic tank and trees - 3 meters (1 meter to bushes).
  • Between the septic tank and a reservoir with running water (stream, river) - 10 meters.
  • Between the septic tank and a body of standing water (lake, pond) - 30 meters.
  • There is 5 meters between the septic tank and the underground gas main.

The main operating characteristic of a septic tank, on which its performance, the efficiency of wastewater treatment and the frequency of pumping will depend, is volume. It is calculated based on the number of household members, daily consumption rates and the capacity of the structure. By sanitary standards one person consumes 200 liters (0.2 mᶟ) per day. Throughput is the capacity of sedimentation tanks with a three-day reserve, plus a small increase for bottom sediments. To operate normally, a septic tank for a family of four requires a volume of 2.7 mᶟ (0.2x4x3+0.3=2.7). The volume of all chambers is calculated, but from the bottom to the level of the overflow pipes. To be on the safe side, you should add on the salvo drop or the arrival of relatives and make the volume a little more than the calculated one, as the super-moderator of our portal’s forum advises.

Vadim (spb) Super moderator FORUMHOUSE

Three cubes are enough for four people.

Options for choosing a septic tank

If the location of individual treatment facilities is regulated by standards, and the volume is selected depending on the amount of wastewater, then what type of septic tank will be, the design of the system and the method of organizing soil filtration depends, first of all, on the groundwater level (GWL) and the throughput (filtering) capacity of the soil. At low groundwater levels, almost any composite or monolithic structure is allowed. But if the soil has weak permeability (clayey soils), then it is necessary to increase the area of ​​the filtration field, the length of the filtration tunnel or the layer of drainage cushion under the filtration well.

If the groundwater level is high, then it is permissible to use only monolithic septic tanks (reinforced concrete, plastic containers) with several chambers and an additional sealed storage. From the storage tank, through a float drainage pump, the settled wastewater will flow to embankment field filtration (cassette and tunnel infiltrators are used). Underground filtration directly from the septic tank in a situation with close occurrence of perched water is unacceptable.

Ladomir Moderator FORUMHOUSE

It is necessary that the distance from the bottom of the filter structure to groundwater is at least a meter.

Popular types of homemade septic tanks

Among the participants of our portal, three types of homemade products are most in demand:

  • From concrete rings;
  • Monolithic reinforced concrete;
  • Plastic (from Eurocubes).

Construction of a septic tank made of concrete rings

When the State Administration allows, the majority of forum users give preference to concrete rings, from which two sealed chambers and a filtration well are usually assembled, connected to each other by overflow pipes. To get the most impermeable structure possible, choose rings with a groove connection; they are not only more resistant to possible ground movements, but it is also easier to achieve the tightness of such a seam. Use external and internal waterproofing bitumen primers or solutions based on CPS with the addition liquid glass. There are two options for the arrangement of cameras - sequential and combined.

In the first, settling tanks are placed one after another, and the FCs are placed at a short distance, each with its own neck and inspection cap. The optimal design for a septic tank of this type was developed by one of the participants with the nickname MatrasMSA with the help of a moderator Ladomira.

MatrasMSA User FORUMHOUSE

The plot is 40x60 meters with a slope, a bathhouse/guest house is currently being built, three people live on weekend visits and sometimes guests, in the future there will be a house for permanent residence. The groundwater level is low, it is problematic to get to the water, the well is 88 meters deep, according to neighbors, the soil is loam. I am planning a septic tank like this: the first and second wells are three rings each (1.5 m in diameter) with a concrete bottom, the third well is the same, but the bottom is on the ground.

During the discussion, the following typical recommendations for the device were given.

Ladomir

  • A straight tee is placed on the pipe entering the septic tank, the lower part is buried 15-30 cm into the drains, similarly on the outlet pipe.
  • The outlet from the septic tank is 5-10 cm lower than the entrance to it, measured along the lower pipe tray.
  • The overflow between the chambers is done at a depth of 0.4 m from the height of the drain column in the septic tank.
  • The height of the drains into the septic tank is the distance from the bottom to the bottom tray of the pipe coming out of the septic tank.
  • The branch pipe entering the filter well does not need to be equipped with a tee; it is routed in such a way that the wastewater flows into the center of the FC.
  • Under the filter well, gravel/crushed stone is added, 0.3-0.5 m thick, and sprinkled on the sides, in a layer of up to 0.2 m.

The combined septic tank (designed by A. Egoryshev) is compact due to the arrangement of sedimentation tanks and FC in a triangle and is suitable for small areas. All wells are closed with blind covers, in which inspection holes are cut out, a common neck (service well) is installed on top, and the fan riser is discharged through the cover of the service well. To prevent differences between settling tanks, the bottom of the pit is filled with concrete slab with a hole for the FC, a drainage pad (filter cassette) made of ASG, 10 cm thick, is poured under the slab, on double layer geotextiles.

On our portal this scheme was proposed by a craftsman with the nickname s_e_s_h, having laid out the design and a similar construction process back in 2009, it is “alive” to this day, which proves the relevance of systems of a similar operating principle.

s_e_s_h User FORUMHOUSE

The requirements for the septic tank, taking into account the standards and needs of the family, were as follows:

  • Good treatment of domestic wastewater at the outlet of the septic tank.
  • Volume sufficient for permanent residence in the house for 3-4 people (bath, shower, 3 sinks, washing and dishwasher, 2 toilets).
  • Winter operation.
  • Robust design with the possibility of easy maintenance of the septic tank itself and underwater communications.
  • Neat and discreet final appearance.
  • Minimum possible cash costs.

The result was an economical design without sacrificing functionality.

However, both options are only suitable for areas with low level groundwater, with a high groundwater level, no matter how well you isolate the wells, there is a danger of them being flooded with perched water and polluting the area with wastewater.

Work of a reinforced concrete septic tank

Monolithic reinforced concrete septic tanks can be used at any level, only the location of the filtration structures will differ. It is difficult to resolve difficulties when digging a pit, but it is possible.

researcher User FORUMHOUSE

To make it faster, the pit is dug with a tractor, on one side it is dug with a bucket that is wider and half a meter deeper than the bottom of the main pit for the septic tank (it seems like a pit), and a regular drainage pump is installed there. All the water from the main pit quietly migrates into the pit and is pumped out from there by a pump and poured out 25-30 meters away. For the duration of work in the pit, pouring and treating hardened concrete with water repellents, this solution is just enough.

Otherwise, the process is standard - formwork, reinforcement cage, pouring with the addition of modifiers to the solution, waterproofing (internal and external). Monolithic structure at low GWL selected by a portal participant Rybnik.

Rybnik User FORUMHOUSE

From the foundation to the rotary well (PW) - 1.4 m, the PW itself has dimensions of 1x1 m, from the PW to the septic tank there is a trench, 7.5 m long, 40 cm wide and 1 m deep. The pipe will enter the septic tank at a depth of 85 cm from surface (taking into account a slope of 2 cm per 1 meter). A second pipe (from the house) will also enter the septic tank. Next, a pipe of clarified water comes out of the septic tank, which will run 23 m along the fence and enter a filter well measuring 1.5x1.5x4 m.

For the reinforcement frame, rods with a diameter of 8 mm were used, restraints (frogs) were bent from them, cement M500 (intended, among other things, for concreting underwater structures in a fresh environment), a special additive that reduces the permeability of concrete, was used for pouring. Flat slate sheets are used as formwork. Details of the process and a step-by-step photo report are in the topic