A modern country house is equipped with many technological benefits that were unavailable even a couple of decades ago and the functioning of which requires water. In addition to cooking and washing hands, there is at least a shower, a washing machine, and maybe also a dishwasher. For all these devices, it is necessary to establish not only the supply of clean water, but also the drainage of the resulting wastewater. This means that the usual level of convenience cannot be imagined without a modern device for treating household wastewater. When it is impossible to connect a house to a central collector, a septic tank made of reinforced concrete rings can be one of the few ways that allows you to properly process waste and prevent soil contamination.
View of a septic tank made of concrete rings in the courtyard of a private house Source mirhat.ru
How does a septic tank work?
For a small private house, a septic tank made of concrete rings is installed according to the classic scheme, including two tanks. If a significant volume of wastewater is expected, three tanks (wells) are installed, different in design and functionality. The first two wells are made hermetically sealed; in the third, a crushed stone filter is installed, through which the water flows into the soil.
The principle of constructing a septic tank made of concrete rings Source admiral-oz.ru
Purpose and design of cameras
- The first septic well serves to receive and settle wastewater. Here, thanks to the work of anaerobic bacteria, sedimentation occurs and partial treatment of wastewater occurs (Anaerobic bacteria are able to decompose complex organic matter into simple substances without access to oxygen). The initially clarified water flows into the second section. The volume of the chamber should be equal to half of the total planned volume of the system; its base is concreted.
- In the second well (drainage) with sealed walls and bottom, additional filtration occurs. Additional filters made of gravel can be installed here.
- In the third well, final filtration occurs. The bottom here is not concreted; a sand-crushed stone (or sand) mixture is poured in for final filtration.
Advantages and disadvantages of a septic tank made of concrete rings
Due to the features of use, design and installation, such a system is the optimal solution in many cases.
Let's consider all the pros and cons of septic tanks made of concrete rings:
Its advantages include:
- simple installation and use technology. There is no need to supply electrical power, arrange additional drainage, or install a pump;
- reliable autonomous design with high mechanical strength;
- complete freedom in choosing the dimensions of the structure;
- long service life;
- large useful volume and easy maintenance;
- resistance to aggressive wastewater environment;
- the weight of the rings is a guarantee that groundwater will not displace the septic tank from the soil;
- available materials and reasonable price for building a septic tank.
Video description
Additionally, the septic tank can be improved - example in the video:
Disadvantages of concrete septic tanks:
- Weight of building material. During installation it is difficult to do without construction equipment.
- The need for high-quality sealing of seams between rings and joints with pipes.
- Hygroscopicity of concrete, which does not allow the method to be used in flooded areas.
- The need for regular cleaning of containers and pumping out wastewater.
Making the right calculations: capacity and design
At the design stage, a septic tank diagram is created from concrete rings, then the volume of the future device is determined:
Number of cameras
The number of cameras depends on the number of people using the sewer system. If a family actively uses the shower, bathtub, and appliances, the drain down the drain will be significant. The drains will require thorough cleaning, for which you will need a septic tank of three wells, two of which will be settling chambers.
Diagram of a septic tank made of concrete rings Source tolkobeton.ru
Capacity
To determine the volume of wastewater entering the septic tank from the kitchen, bathhouse and toilet, you need to calculate the daily water consumption. Knowing that the daily rate of domestic water consumption for one resident is equal to 200 liters, it is easy to calculate that a family of 4 people will fill the septic tank at a rate of 800 liters per day.
The quality of the septic tank improves if wastewater lingers in the chambers for a long enough time. By increasing the volume, you can improve the quality of the wastewater and protect the system from clogging with difficult-to-decompose fat.
According to building codes, the installation must accommodate wastewater that is generated over three days (the daily flow rate must be multiplied by 3). This number determines the volume of the septic tank and the number of chambers:
- a single-chamber septic tank is installed if daily waste does not exceed 1 cubic meter;
- two-chamber – up to 5 cubic meters;
- three-chamber – 8 or more cubic meters.
In a septic tank with two chambers, the first sump occupies the volume of 2/3 of the entire septic tank, in a three-chamber septic tank - half.
What to pay attention to before starting work
If the area has a high aquifer:
- The seams of the septic tank are carefully sealed, otherwise it will constantly be recharged with groundwater and overflow. There will be additional costs for calling a sewage disposal truck.
- The installation of a filtration well becomes meaningless; For additional treatment and drainage of water from the septic tank, another option is needed.
Video description
About septic tanks on high groundwater in the video:
Increased structural strength:
- To protect the building from possible ground movements and shifting of the rings, they are additionally secured with metal ties.
- To reduce the subsidence of the septic tank and improve its thermal insulation and drainage, during installation a cushion of sand, crushed stone or gravel is placed around it.
How much will the rings cost?
Concrete rings are selected based on calculations of the volume of the septic tank. The dimensions of concrete rings for a septic tank are indicated on the marking. They are characterized by the height, diameter and thickness of the walls of the structure, as well as the type of product:
- KS – wall ring, suitable for erecting walls;
- PP – floor slabs;
- PD – road slabs, installed at the bottom of the pit.
The cost of concrete rings is affected by their size and location of production. Reinforced concrete rings with low surface permeability, resistant to aggressive environments, are suitable for sewerage.
The height can be 290, 590, 800, 900 mm. A typical product with a height of 900 mm can have a diameter of 700, 800, 1000, 1500 and 2000 mm. The average price for it varies from 1200 to 1800 rubles. Rings with other parameters can cost from 680-1050 to 1500-2400 rubles.
Rings for septic tank Source humphrey.alpvd.ru
It should be remembered that some rings are marked with an internal (useful) diameter, while others have an external diameter, which is important for selecting caps. The average cost of a reinforced concrete cover or polymer hatch ranges from 1,700 to 2,000 rubles.
When drawing up an estimate for a septic tank made of concrete rings, the price takes into account additional materials: pipes, cement, sealant, as well as the cost of work (digging, installation of rings). The final average price of a turnkey septic tank is in the range from 38,000 to 69,000 rubles.
What other materials will you need?
In addition to the required number of reinforced concrete well rings and slabs with a hole for the hatch, additional materials are needed:
- sand, gravel, cement, crushed stone for the “pillow”;
- cement, liquid glass for sealing seams between rings;
- sealed (polymer) hatches;
- shovels, hammer drill;
- pipes and fittings.
Construction stages
Installation is carried out in the following order:
- A location is selected, an installation diagram is drawn up, and the parameters of the septic tank are calculated.
- A hole is dug.
- Rings are installed, pipes are supplied.
- Sealing and waterproofing work is being carried out.
- Floors are being installed.
- Backfilling is in progress.
Video description
The work procedure and installation of a septic tank made of concrete rings in the video:
How to choose the optimal location for a septic tank
The structure is mounted above the groundwater level. The best location is at the maximum distance from the house (at least 7 meters, but no more than 20, so as not to increase the cost of pipeline construction). It is logical to place the septic tank on the border of the site, next to the road. This will reduce operating costs, since the cost of leaving a sewage tank is affected by access to the system and the length of the hose. In addition, with the correct location, the sewage disposal truck does not need to enter the yard, and the hoses will not lie on the beds or paths (otherwise, when the hose is rolled up, waste may end up in the garden).
The distance to the nearest source of drinking water (well, borehole) is at least 30 (and if possible more) meters.
Pit preparation
Ground work using an excavator takes 2-3 hours. The size of the pit should be slightly larger than the dimensions of the wells. This is necessary for the smooth installation of the rings and their waterproofing. The bottom is covered with crushed stone and concreted.
Preparing a pit for a septic tank made of concrete rings Source rostovgruz.ru
Installation of rings and sewer pipes
Rings for a septic tank are installed using lifting equipment, which significantly saves time (when compared with manual installation). Fixation of the seams is ensured with cement mortar; additionally, metal ties (staples, plates) are installed.
Holes are punched in the rings and plastic overflow pipes are installed. They have a curved shape and work on the principle of a water seal.
The crucial moment is the process of installing rings Source remoskop.ru
Sealing and waterproofing
The seams of a septic tank made of concrete rings are sealed on both sides of the structure. For this purpose, cement and coating protective solutions are used. You can install ready-made plastic cylinders inside the well. This additional cost will make the system 100% sealed.
In the process of waterproofing concrete rings for a septic tank, the connections are treated with liquid glass, bitumen or polymer-based mastic, and concrete mixture. To prevent freezing (and destruction) of the structure in winter, it is recommended to insulate it with a layer of polystyrene foam.
Sealing joints and waterproofing septic tanks made of concrete rings Source zen.yandex.ru
Hatch installation and backfilling
The wells are covered with concrete slabs, with holes for hatches. In the first two wells, ventilation is installed, which is necessary for the removal of methane (gas appears as a result of the activity of anaerobic bacteria). To backfill the installed floors, use soil taken from the pit (backfill).
Backfilling of finished wells Source lanshaft.com
How to put a septic tank into operation
In order for the system to begin to function effectively, the constructed septic tank must be saturated with anaerobic microflora. The natural accumulation process takes several months, so it is accelerated by saturating the septic tank with imported microflora. You can do this in two ways:
- The new septic tank is filled with wastewater and left for 10-14 days. Then sludge sludge from an existing anaerobic septic tank is loaded into it (2 buckets per cubic meter).
- You can purchase ready-made bioactivators (bacterial strains) in the store (the main thing here is not to confuse them with aerobes, which are intended for other treatment systems).
Ready-to-start septic tank made of rings Source remont-book.com
What rules must be followed when servicing a septic tank?
There are simple rules that support the high-quality operation of the system.
- Cleaning. Twice a year, in addition to cleaning the drains, the septic tank must be inspected and the pipelines cleaned. Once every 5 years (or better yet, every 2-3 years) the bottom heavy fats are removed. The volume of sludge should not exceed 25% of the tank volume. When cleaning, part of the sludge is left to restore the microflora.
- Quality of work. The wastewater leaving the system must be 70% purified. Analysis of wastewater in the laboratory will determine the acidity indicator, which will allow you to find out the quality of the drainage system.
- Security measures:
- Work inside the septic tank is allowed only after intensive ventilation and using a safety belt (gases formed inside can be dangerous to human life).
- Increased safety measures are required when working with power tools (humid environments).
A septic tank made of concrete rings makes private housing more autonomous and, despite its shortcomings, it is one of the most reliable and durable options for treatment facilities for suburban real estate.
Most private houses do not have a central sewerage system, which leads to significant difficulties with wastewater disposal. What to do in such a situation? In such cases, an autonomous sewage system is organized: a centralized collection of wastewater from all domestic and outbuildings on the site is carried out, which is disposed of in a cesspool.
Cesspools are the most common, but time does not stand still and they have been replaced by septic tanks. Septic tanks can be prefabricated plastic, as well as with deep cleaning stations.
Their disadvantage is their very high cost. An alternative option is to install a septic tank made of concrete rings.
Pros and cons of a concrete septic tank
Positive sides:
Reliability of the design. Reinforced concrete has high strength, durability and is able to withstand aggressive environments.
An overflow septic tank made of concrete rings is completely autonomous; it does not require additional elements for operation, such as electricity, pumps, drainage systems, containers for aeration and bacteria, etc.
Possibility of constructing septic tanks of various sizes and types. This is due to the wide variety of reinforced concrete rings: the diameter of the rings ranges from 0.5 to 2 meters. The height of the rings has two options - 0.6 and 0.9 meters.
You can build a small septic tank yourself, even without the involvement of heavy equipment. Installation does not require special skills or knowledge.
The septic tank is easy to operate - no human intervention is required.
A minimum set of materials and tools is required for construction.
Negative sides:
For the construction of large-capacity septic tanks, manipulators are required. This is due to the large mass of concrete rings and slabs.
At least two people are required for installation. Such septic tanks require periodic cleaning.
Septic tank layout and operation
Before starting work, it is necessary to decide on the location and schematic diagram of the septic tank made of concrete rings. It is worth remembering that the concrete septic tank must be located at least 5 meters from the house, at least 2 meters from outbuildings. If there are local sources of water supply: 30 or more meters from wells and boreholes.
The minimum distance between the septic tank and the roadway is 5 meters. The septic tank must be located directly on the site.
Septic tanks are single-chamber, double-chamber and three-chamber. An example of each type of septic tank made of concrete rings can be viewed in numerous photos of our selection at the end of this article.
The construction of more chambers is not advisable. The most popular are two-chamber septic tanks. Such septic tanks consist of two wells, between which there is a connecting pipe at the top.
The first well receives wastewater collected from all sources in the house. It is sealed (has a concrete bottom). As the first well is filled, the wastewater settles, and the wastewater decomposes into liquid, solid and gaseous parts.
The solid part is accumulated at the bottom, the liquid part is at the top, and the gaseous part is removed through a ventilation riser located at the very top of the septic tank (a hole is made in the well floor slab, the pipe is brought out 0.5-1.0 meters above the ground surface).
Having reached the mark of the connecting pipe, the liquid part is poured into the second well. The second well has a drained bottom (there is no concrete slab in the bottom - instead there is a crushed stone cushion).
As liquid waste flows in, it accumulates, settles and is absorbed into the soil. How to make a septic tank from concrete rings? It all starts with calculating the required volume.
Required volume
Depending on the volume of wastewater, the total volume of the septic tank is selected. For a standard family of 3-4 people, a septic tank of about 6-9 cubic meters is required. The calculation is based on the conditions of water consumption per day per person: 200 liters/day, as well as the minimum volume of the receiving waste pit for three days.
If there are 4 people, we get the total maximum volume of wastewater, taking into account a reserve of 200 liters - 1 cubic meter. This means that the receiving well must be at least 3 cubic meters.
The second well is usually made with the same volume. If there are more people, the number of rings in the septic tank and their diameter are increased, and additional chambers are erected.
The maximum volume of a three-chamber septic tank can reach 45 cubic meters of useful volume.
Preparation
After determining the location for the septic tank and calculating the required volume of wastewater, you can easily determine the required volume of the septic tank. The number of concrete rings, slabs for the bottom and covering depends on its volume (you can use ready-made rings with bottoms).
After purchasing and receiving all materials, you must:
Prepare the pit. It is worth digging a pit for all chambers at once (a large pit), with a margin of 0.5-1 meter for mounting rings on each side. The depth of the pit must correspond to the full height of the septic tank.
Level the bottom of the pit and cover it with a sand cushion 0.1-0.2 meters thick. Press down the pillow.
Digging of a pit should be carried out only by mechanized methods. When constructing septic tanks of small volumes (up to 4 cubic meters), you can do it manually.
Buy cement, sand, crushed stone, sewer pipes, bitumen mastic, well hatch. Make sure you have the necessary tools.
Septic tank installation
To build a septic tank, you need special equipment and at least 2 people. Installation is carried out from the bottom. The bottom is set to level. Further:
Installation of rings and coatings is carried out using manipulators. The rings are mounted on a cement-sand mortar, just like all covering slabs.
After installing the rings, perform coating waterproofing, protecting both the septic tank itself from moisture and preventing wastewater from getting through the walls of the septic tank into the ground.
The connecting pipe between the septic tank wells should be located at least 0.2 meters below the inlet pipe from the house to the receiving well. Make a drained bottom of crushed stone in the last well.
Seal the edges of the holes for pipes in the walls of the septic tank with cement mortar. After it has hardened, thoroughly coat this area with bitumen.
Maintain the slope of sewer pipes within 3-5%.
Conclusion
A concrete septic tank does not require a lot of time and money. It is a budget option for solving sewage problems.
Installation of small septic tanks made of concrete rings can be done with your own hands, without the use of special equipment.
Upon completion of the work, the septic tank must be equipped with ventilation pipes, the rings must be fastened together with longitudinal vertical corners or plates. It is most rational to place the septic tank at the lowest point of the site.
Photo of a septic tank made of concrete rings
Issues of waste disposal in suburban areas concern both summer residents and owners of private houses. Most dacha areas and many small settlements in the country are not provided with the ability to connect to centralized networks. It’s hard to come to terms with this situation, isn’t it?
A two-chamber septic tank made of concrete rings, the construction of which will require a minimum of money and effort, will allow you to get rid of problems. You can build such a system with your own hands without any problems. However, even if you plan to attract workers, it is simply necessary to know the rules and features of the device. After all, the structure must operate without failure.
We suggest that you familiarize yourself with reliable information about the construction of concrete septic tanks, the basics of designing an autonomous treatment plant and its organization. In addition to valuable information, we have selected photos, diagrams and video tutorials.
A septic tank, consisting of two chambers, is a practical treatment facility capable of processing organic waste.
The cleaning mechanism is based on the operation of two communicating compartments, inside of which the liquid component and the insoluble solid component are separated by settling.
Image gallery
Andrey Anatolyevich Ratnikov is an engineer who has been working since 1984 in companies related to waste disposal. Education and experience allowed him to develop his own septic tank design using concrete rings. The settling tank is made according to the classical design, but the essence of the invention is a filter well. When you read this article, it will become clear that everything ingenious is simple.
For an autonomous sewage system for a country house, it is not necessary to buy expensive industrial stations. A two-chamber septic tank made of reinforced concrete rings can handle wastewater treatment. It is important to arrange it correctly and calculate the performance. The design of the receiving chamber shown in the picture is classic.
An important role in the correct design of a septic tank is played by tees installed on the inlet and outlet pipes
You can see the sediment that has fallen, with particles floating on top that have not settled. To prevent the crust from going into the filter well, a tee is installed at the outlet, and another one at the inlet directs wastewater down. The second function of tees is to provide cross ventilation of the septic tank. It is important to prevent odors from decaying organic matter from getting outside and into the house.
A treatment plant is allowed to be installed if the soil water is at a depth of 3 meters or more. When, when digging a pit, wet soil is discovered at a shallow depth, construction will have to be abandoned.
In the hole under the septic tank, level the bottom and fill it with sand to an approximate thickness of 15 cm. Pour water, so the sand will sink as much as possible. Not all purchased rings have a concrete bottom, so you will have to make it yourself and waterproof it. The upper ring is installed on the mortar or, better yet, special inserts are used to seal the seams.
Useful volume of septic tank
The capacity of a septic tank required for full functioning is calculated using a well-known formula. It must ensure the intake of wastewater, the volume of which is equal to the three-day water consumption of one person. According to the norm, one family member uses 200 liters in 24 hours, respectively, 600 liters in 72 hours. The last value is multiplied by the number of residents and the required volume of the receiving chamber is obtained.
In these calculations lies an error that is often not noticed, and then they are surprised that the septic tank does not cope with its task.
Advice. They calculate the total volume, losing sight of the fact that the container is filled with waste only to the lower level of the supply pipe. It is this volume that is useful, and it is taken into account in the calculations.
Important! The minimum depth of the septic tank from the top of the drain to the bottom is 1.2 m, the smallest diameter of the ring is 1 m. The greatest depth is 2.5 m.
Table of sizes and volumes of well circles suitable for installing septic tanks:
| Brand | Outer diameter, mm | Inner diameter, mm | Wall thickness | Height, mm | Weight, t | Volume, m3 |
| KS 10-3 | 11600 | 1000 | 80 | 290 | 0,2 | 0,10 |
| KS 10-6 | 11600 | 1000 | 80 | 590 | 0,4 | 0,16 |
| KS 10-9 | 11600 | 1000 | 80 | 890 | 0,6 | 0,23 |
| KS 15-3 | 1680 | 1500 | 90 | 290 | 0,32 | 0,14 |
| KS 15-6 | 1680 | 1500 | 90 | 590 | 0,67 | 0,26 |
| KS 15-9 | 1680 | 1500 | 90 | 890 | 0,96 | 0,40 |
| KS 20-6 | 2200 | 2000 | 100 | 590 | 0,98 | 0,39 |
| KS 20-9 | 2200 | 2000 | 100 | 890 | 1,47 | 0,59 |
Rings with a diameter of 1.5 m or more are most suitable for constructing a septic tank, but they are inconvenient to work with - they are too heavy. The solution is to use smaller circles. To achieve the required volume, the structure is planted at a greater depth.
It is better to go the other way: connect 2 containers in series, the capacity of which will be equal to the required one. You will get a septic tank of two chambers, which works similarly to a single-chamber one.
A.A. Ratnikov, technical director of SPO BioStroy LLC
Inlet and outlet tees
Holes are provided in the hatch cover directly above the tees. This allows you to clear them directly from the surface if they become clogged. The inlet tee plays an important role:
- drains are directed downward without destroying the crust;
- it does not clog the pipe when wastewater is discharged intermittently;
- easy cleaning from the outside without going into the well.
In the transition pipe to the filter container, sometimes a corner is installed instead of a tee. This is a mistake: when it is in the drains, the ventilation is blocked. Installing a simply open pipe is also wrong:
- the crust is destroyed;
- its pieces pass into the filter well;
- the pipe may become clogged.
The use of tees allows you to increase the useful volume of the septic tank. It is enough to place the overflow pipe just 5 centimeters below the inlet pipe. Water that is under the crust will enter the tee It is important to choose the correct dimensions of the tees for the septic tank. If they are not long enough, they do not provide crust retention; large sizes interfere with the formation of a proper settling zone, and the sediment at the bottom becomes agitated.
Filter well
Standards indicate that filtration tanks can be installed if the volume of wastewater does not exceed 1 m 3 per day. Another condition is sandy or sandy loam soil. This provision formally prohibited the construction of filter wells in areas with different soil. Practice refutes this norm: structures work normally even on loam. Obviously, the rules took into account the small design drainage area.
The filter well can be built differently. Instead of placing the crushed stone filter inside the circle, where the area is limited by its size, it is increased. This is done in simple ways:
- the hole is not dug 25 cm larger than the diameter of the circle, but much wider;
- the bottom filter is placed not inside the well, but outside;
- the bottom ring is made (bought) with holes in the walls.
This allows you to significantly increase the filtration area. With this design, the well is more of a distribution well - it transfers wastewater to a filter that is significantly larger than its size. This allows the height of the structure to be reduced.
Ratnikov filtration well. The numbers indicate: 1 – water shield; 2 – neck rings; 3 – hatch; 4 – insulating cover; 5 – overlap; 6 – ventilation riser; 7 – blind circle; 8 – ring with holes; 9 – bottom filter; 10 – holes in the circle; 11 – concrete foundation; 12 – supply pipeline The waste flows out of a pipe that is located 10 cm or more above the filter. Its end is placed in the middle of the container. The jet falls not on crushed stone, but on a flat divider. It is made from a piece of any material heavier than water that is resistant to moisture.
Bottom filter
The correct choice of the bottom filter area is important. Only if it is of sufficient size will it ensure reliable functioning of the structure. You can use the table below, which shows how many liters of wastewater can be filtered by 1 m2 of soil, depending on its composition.
The inner surface area of a ring with a diameter of 1.5 m is 1.75 m2. If you install a bottom filter 2 m in circumference, this is already 3 m2 of filter, which will allow you to purify about 60 cubic meters of wastewater per day on clay, and 450 m3 on coarse sandy soil Proper ventilation device
To prevent a bad smell in the house and on the street, Ratnikov advises installing a pipe on the filter chamber, which serves for air flow. It flows through it into the well, then through the connecting pipeline into the septic tank. It comes out through the top of the tee, which is never flooded with water. If there is no gap in the sump cover, the air continues to move through the pipes. It enters the supply line tee and goes into the house. The release of gases into the atmosphere occurs through a waste pipe, which is installed in the room and discharged through the ceiling and roof.
This is what cross-ventilation should ideally look like, when air enters the filtration well and is exhausted through the fan riser There are three versions:
- If the system is gravity-fed, then the supply pipe is installed on the filter tank. The second one on a septic tank is unnecessary and harmful: the air will rush upward, where it meets no resistance.
- If the water supply system forces you to install a filter well on a hill, then when located close to the septic tank, the pump pressure pipe is laid in a thicker one. Air will flow through the latter. The scheme is the same: inflow into the filter tank, exhaust through the fan riser.
- When the second chamber is at a great distance, one inflow is installed on a container with a pump, if it is in a separate well, or on a septic tank, the second on a drainage tank. There is also a high-height exhaust, and the inflow is lower to create draft.
It is wrong to install a “fungus” on the hood, which becomes completely clogged with frost in winter. An open pipe always leaves a hole, albeit a small one.
If cross ventilation is not arranged, gases break out through all the cracks that are in the septic tank, filter well, and through the sewer system in the house. The problem is especially typical for dachas, where residents come occasionally. During your absence, the water in the siphons evaporates and naturally draws all the aromas from the septic tank into the house.
Answers on questions
Question No. 1. The standards of the STO Novostroy state that a properly constructed septic tank works for 20 years, during which time there is no need to change the filter material or remove soil. Is this true?
True, although the standards are cautious in assessing the operating time of a septic tank. In fact, it can last longer if you strike a balance between the amount of waste and organic matter coming in and the ability of bacteria to process it. Usually, improper operation leads to disruption of normal operation: the number of residents increases or large quantities of harmful substances that destroy microflora begin to be poured into the sewer system. Untimely removal of sediment also shortens the service life of the septic tank and disrupts cross-ventilation.
Question No. 2. If the slope of sewer pipes is made more than 2 mm per meter, why is this bad?
This threatens to clog the pipes. Water quickly runs through the pipeline, but the solid fractions do not have time to leave together and remain on the walls.
Sometimes connecting a private house to a centralized sewerage system is impossible, and in this case the only connection alternative is a septic tank or treatment plant, as it is called. From this article you will learn how to properly make a septic tank from concrete rings with your own hands, without involving a contractor, about the work scheme and purpose of the treatment plant.
The need for septic tanks in the absence of a centralized sewage system is due to the fact that wastewater contains various kinds of organic substances, the ingress of which into food or drinking water entails serious problems.
Before wastewater penetrates into the ground, it must be cleaned and neutralized. This is the purpose of the treatment plant. 
Here, the organic component of fecal and sewage accumulations is separated into safe sludge and water suitable for irrigation of the territory. The septic tank as such does not affect its contents, but it creates conditions in which bacteria develop, decomposing organic matter into safe elements.
The choice of location for a septic tank is regulated mainly by SNiP 2.04.03-85 “Sewerage. External networks and structures.”
In addition to compliance with the regulations of this document, you need to obtain a hygienic certificate, which gives the right to install a treatment station in the selected location, as mentioned in SanPiN 2.1.5.980-00.
Here: V is the volume of a separate section of the septic tank, Y is the rate of water consumption by one person (conditional), Z is the maximum number of people living in the house.
Septic tanks installed in accordance with this formula are very large, but they provide maximum purification of fecal and sewage wastewater, turning it into water suitable for irrigation of the site and sludge that serves as fertilizer. The rate of water consumption is determined by many parameters.
Indoor water supply and sewerage systems in buildings meet the conventional norm of 95–300 liters per person per day.
You can calculate on your own how much water you consume, or use the SNiP table. 
When thinking about installing a septic tank made of concrete rings, it is better to stick to the maximum values and increase the number of residents by 50%. Although this will increase the cost of building a septic tank, you will eliminate the risks: if guests arrive, the septic tank will not overflow and the ground near the building will not be flooded with feces.
Some experts use the formula mentioned above, but it is used to calculate the total volume of a station consisting of several sections, for example, a two-chamber septic tank made of concrete rings.
With this approach, construction costs are significantly reduced, and the degree of wastewater treatment becomes worse as the number of residents increases. 
If purified water is supposed to be discharged close to buildings and water intake points (up to 50 m), use the formula in relation to the volume of one section.
If the distance is greater than 50m, you can use the formula for the total volume. Untreated wastewater removed at such a distance will not be dangerous.
Types of septic tanks made of concrete rings
Several types of septic tanks are built from reinforced concrete rings, and the stations differ:
- depth level;
- ring diameter;
- insulation.
The depth of the septic tank is determined both by its dimensions and winter temperatures, more precisely, by the depth of soil freezing. 
The lower it is, the lower the septic tank needs to be installed, since a strong drop in temperature (less than zero degrees) slows down or even stops the processes occurring in each section. Therefore, it is necessary to either deeply bury the septic tank - all its sections, or insulate each section with polystyrene foam or similar insulation.
You can reduce the cost of installing concrete rings under the septic tank if the station is deeper if you install not reinforced concrete rings above the freezing depth of the soil, but a brick well, since above the freezing depth of the soil the processes in the septic tank are greatly inhibited even with high-quality insulation.
Septic tanks are also classified according to the number of their elements. Single-element ones are called cesspools and are considered ineffective. 
The most effective designs are made of three elements. A larger number of sections does not affect the quality of wastewater treatment. Three sections can be placed in the longitudinal direction, in which case the installation is very long, or in a triangle, when the area of the pit for the septic tank is reduced by almost a third, and with it the volume of soil that needs to be dug.
If you need a small volume septic tank, make a single-chamber septic tank from concrete rings. A wall with an overflow hole is placed inside the rings. It divides the space into a pair of chambers.
Construction of septic tanks from concrete rings
Although you will have to rent construction equipment to manipulate concrete rings under the septic tank, if you build the structure yourself, you will be able to save money.
The construction of a sewage treatment plant is a fairly simple task for someone who has at least some knowledge of construction, plumbing and reinforced concrete work. 
The necessary calculations are extremely simple and approximate; they can be performed even by a schoolchild. The key condition for installing a septic tank is the flow of waste into it by gravity.
That is why the optimal slope between the sewer exit from the building and the entrance of the septic tank is considered to be from 1 to 3 cm/m. You can build a septic tank on a hill, but in this case you cannot do without installing a pump and valves that block the flow of wastewater in the opposite direction.
Preparing a pit for a septic tank with concrete rings
Having determined the volume of the treatment plant, think about how the treated water will be discharged. You can supply it to the site using a pump, or by pouring it directly onto the ground.
In the second case, digging septic tanks from concrete rings requires digging not only a foundation pit, but also trenches for laying drainage pipes that carry wastewater 10–20 m from the foundation of the treatment plant. Discharging water near the foundation will cause it to subsidence and cause damage to the septic tank. 
It is necessary for the water to flow by gravity through the pipes, and in the place where the wastewater is discharged, a hole must be dug (below the pipe) with a length, width and depth of 1 m.
The hole should be filled with sand or fine crushed stone, after which a pipe must be laid, filling it at least 1 m above its level, to the top.
After you have managed to select and buy concrete rings for the septic tank, you begin to dig a pit. Concrete rings are selected based on the area sufficient for the septic tank and allowing deep digging. 
If the site has rocky soil, it is better to lay the widest rings. Products of the KS-30-1 brand with an internal diameter of 3 m are suitable.
If there is little free space, if the soil is sandy, loamy or clayey, it is better to dig a pit as deep as possible, choose rings of the KS-10-9 brand with an internal diameter of 1 m.
It is necessary to determine in advance the location of each column, taking into account the distance between adjacent ones of 50 cm, which is required to protect the septic tank and insulate it during soil shifts.
To the calculated depth of the well, it is necessary to add the depth of freezing (to maximally protect the treatment station from heaving in frost) and the concrete-crushed stone cushion (approximately 0.2 and 0.3 m). The result will be the depth of the pit for digging.
Digging a pit for the subsequent installation of a septic tank from concrete rings on your own is too difficult and time-consuming. It’s easier to rent an excavator - such a machine will cope with the job in a maximum of 3 hours. 
If it is not possible to hire an excavator, you can seek help from a team that carries out excavation work. The cost of services in this case is comparable to the cost of hiring an excavator, but it will take more time.
After constructing the pit and leveling the walls, the bottom of the septic tank should be sealed with concrete rings. If the soil is not rocky, then this stage of work is required so that the foundation of the treatment plant can become strong enough. For compaction, you can use a vibrating plate or a hand tamper.
It is important to fill the hole evenly - do it in small portions of soil on each side so that the rings do not move.
After leveling the surface of the resulting backfill with the nearby soil, wait 2–3 weeks. After the ground has subsided, add soil around the perimeter of the septic tank. The next addition is carried out after the rainy season.
Using, cleaning and repairing a septic tank made of concrete rings
You can use the treatment station immediately after the construction of wells. Septic tanks do not require special maintenance. It is only necessary to monitor the sludge level in the first two chambers once every 3–5 years. 
When lowering into the hatch for inspection purposes, use a gas mask. The smell from a septic tank made of concrete rings is very strong and gas accumulates under the hatch, so without a gas mask you can suffocate.
If the sludge level exceeds half the distance to the outlet pipe, you need to call a sewage disposal machine or scoop out the sludge with buckets.
The sludge obtained from a septic tank is used as fertilizer for non-food plants.
