Septic tank volume. The optimal volume of a septic tank for a private home: calculation rules How to correctly calculate the volume of a septic tank

A septic tank made of reinforced concrete rings consists of several wells in which the rings are installed on top of each other. The first well is a septic tank and is required to be installed, the remaining tanks (their number may vary) are a system of filter wells into which treated wastewater from the septic tank will be poured.

We calculate the volume of the septic tank

The volume of a septic tank is a quantity that cannot be taken from the ceiling or on the advice of neighbors. Calculation of a septic tank made of concrete rings is regulated building codes, is individual for each user and depends on a number of factors: not only on the number of residents living in the house, but also on the way of life, the degree of improvement of the building, the composition of the soil, the level groundwater, climate zone. Let's sort things out in order.

In our calculations we will rely on such official documents as:

  • Set of Rules 32.13330.2012 (year) "Sewerage. External networks and structures"
  • STO NOSTROY 2.17.176-2015 (year) " Network engineering external Autonomous systems sewers with septic tanks and underground filtration structures Wastewater. Rules for design and installation, control of implementation, requirements for work results,” as well as other relevant documents.

Code of Rules 32.13330.2012 dryly and laconicly tells us the following (clause 9.2.13.3):

ECH - equivalent number of residents (in our case, the number of residents in the house).

If less than 25 people live in your house, then you can calculate the volume of a septic tank made of concrete rings using the formula: daily water consumption by one person, multiplied by the number of people and by THREE days.

As we can see, clause 9.2.13.4 allows us to use a single-chamber septic tank, implying that after “pre-cleaning” our septic tank will be pumped out. Our goal is the operation of treatment facilities without pumping, i.e. complete autonomy. Therefore, it makes sense to use two chambers (1 chamber is a septic tank with concrete bottom, 2 chamber - filter well) or even three chambers (1 chamber - septic tank with a concrete bottom, 2 and 3 chambers - filter wells), despite the fact that SNiP recommends doing this with a larger number of residents.

Water consumption per person is determined according to the Code of Rules 30.13330.2012 “ Internal water supply and sewerage of buildings":

Table A.2 – Estimated (specific) annual average daily water (wastewater) consumption in residential buildings, l/day, per 1 resident

Residential buildings Stoitelno-climatic region
I and II III and IV
general including hot general including hot
With running water and sewerage without baths 100 40 110 45
Same with gas supply. 120 48 135 55
With water supply, sewerage and bathtubs with water heaters running on solid fuel 150 60 170 70
Same with gas water heaters. 210 60 235 95
With centralized hot water supply and sitz baths 230 85 260 105
The same, with baths longer than 1500-1700 mm 250 100 285 115

For most country houses In the Moscow region (II climatic region), this figure will be at the level of 150 liters per day per person. With economical use, the spillway can be reduced to 100 liters per day (possibly less). If you pour it all the way, get ready to drain 250 liters of water per person per day.

The climatic region is determined according to SP.131.13330.2012 “Building climatology”. The average monthly temperature in Moscow in January is -7.8 ˚С, in July 18.7 ˚С. Based on this, we determine climate zone, as IIГ (DVA-GE). You can read more about this on the page in the information section.

For example, let’s imagine that 3 people live in our house.

The volume of the septic tank in this case will be:

  • 3 people * 90 liters/day * 3 days = 810 liters (3 people, economical consumption);
  • 3 people * 150 liters/day * 3 days = 1350 liters (3 people, average consumption);
  • 3 people * 220 liters/day * 3 days = 1980 liters (3 people, maximum consumption).

How many rings will you need?

The calculator for calculating a septic tank made of concrete rings provides fairly accurate data on the number of rings to be laid. Here it is worth considering that the volume of one KS-10-9 ring (Wall ring: internal diameter - 1 meter, wall height - 90 cm) is 3.14 * 0.5 * 0.5 * 0.9 = 0.7 m3 , or 700 liters.

This means that to make a septic tank we need:

  • 2 rings (3 people, economical consumption);
  • 2 rings (3 people, average consumption);
  • 3 rings (3 people, maximum flow).

In this case, the upper ring, purely technologically, is never filled and remains dry. This is due to the fact that the inlet pipe (coming from the house) cuts into the septic tank at a depth of about 70 cm.

This means that we need to add one more ring to our number:

  • 3 rings (3 people, economical consumption);
  • 3 rings (3 people, average consumption);
  • 4 rings (3 people, maximum flow).

This will be your septic tank (the first well shaft), in which the wastewater treatment process takes place. Now, the treated wastewater needs to be drained somewhere...

For this purpose, another shaft (filter well) is being built nearby, into which treated wastewater from the septic tank will be poured. The main requirement for the second container is that it must have time to release all the water entering it into the ground, and all the drained water (and we calculated its consumption above) must be absorbed into the ground! Only in this situation we will not have to pump out our septic tank and we will achieve complete autonomy.

We calculate the volume of the filter well

IMPORTANT! If your site has a high groundwater level, then a filter well is not for you, and for your case you need to use aeration fields.

A filter well passes water into the ground through the bottom, as well as through holes in the walls of the rings. If the filter well is not constructed correctly, the water will not have time to go into the ground and, as a result, it will have to be pumped out regularly, therefore, if one well does not cope with its tasks, then a second one is built nearby (placing more than 4 rings in the shaft is not allowed) .

Or by conducting a simple experiment:

Remove upper layer soil (chernozem) and having reached the bottom layer of soil, roll it into a ball that fits in the palm of your hand:

  • If the ball collapses when squeezed - this is sandy loam
  • If the ball turns into a cake, with cracks along the edges - this is loam
  • If the ball turns into a cake, and cracks do NOT form along the edges - this is clay

Having found out the type of our soil, let’s turn to the table “soil absorption forces” (STO NOSTROY 2.17.176-2015 pp. 25-26):

No. Name of breeds Soil filtration coefficient, m/day Permissible design load per m 2 of filter surface, l/day
Clay soils
1 Clay less than 0.001 Less than 1
2 Heavy loam 0,001-0,05 1-30
3 Light to medium loam 0,05-0,4 30-40
4 The suspension is dense 0,01-0,1 25-35
5 Loose suspension 0,5-1,0 45-55
Sandy soils
6 Silty clay sand with a predominant fraction of 0.01-0.05 mm 0,1-1,0 35-55
7 Homogeneous silty sand with a predominant fraction of 0.01-0.05 mm 1,5-5,0 60-80
8 Fine-grained clayey sand with a predominant fraction of 0.1-0.25 mm 10-15 80-100
9 Fine-grained homogeneous sand with a predominant fraction of 0.1-0.25 mm 20-25 105-110
10 Medium-grained clayey sand with a predominant fraction of 0.25-0.5 mm 35-50 115-130
11 Medium-grained homogeneous sand with a predominant fraction of 0.25-0.5 mm 35-40 115-120
12 Sand is coarse-grained, slightly clayey with a predominant fraction of 0.5-1.0 mm 35-40 115-120
13 Coarse-grained homogeneous sand with a predominant fraction of 0.5-1.0 mm 60-75 130-160
Pebble and gravel soils
14 Pebble with sand 20-100 100-170
15 Sorted pebbles more than 100 -
16 Pebble is clean 100-200 -
17 Gravel is clean 100-200 -
18 Gravel with sand 75-150 160-200
19 Gravel-pebble soils with a significant admixture of fine particles 20-60 105-130
Peat
20 Peat is slightly decomposed 1,0-4,5 55-745
21 Moderately decomposed peat 0,15-1,0 35-55
22 Peat is heavily decomposed 0,01-0,15 25-35

We select the type of our soil and in the rightmost column we determine the amount of “water absorption” in liters per 1 m2 of soil surface per day. In my case, this is loam and 35 liters per m2 per day. Therefore, in order to absorb all the water, we need to distribute it on the following surface of our soil:

  • 3 people * 90 (liters/day) / 35 (liters/day*m2) = 7.7 m2 (3 people, economical consumption, loam soil)
  • 3 people * 150 (liters/day) / 35 (liters/day*m2) = 12.8 m2 (3 people, average consumption, loam soil)
  • 3 people * 220 (liters/day) / 35 (liters/day*m2) = 18.8 m2 (3 people, maximum consumption, loam soil)

The filter well passes water into the ground through the bottom (on which a bottom filter is made from a layer of crushed stone ~20 cm), as well as through holes in the walls of the rings. In order to obtain the required number of square meters of “absorption” surface, we will count the number of required rings.

  • The area of ​​the well bottom is 3.14*0.5*0.5 = 0.7 m2.
  • The surface area of ​​the wall of one ring is 3.14 * 0.9 * 0.9 = 2.5 m2

This means that the bottom ring gives us 3.2 m2 of “absorption” surface, each subsequent ring adds another 2.5 m2, therefore, the number of rings we need:

  • 3.2 m2+2.5 m2+2.5 m2 = 8.2 m2 (>7.7 m2) – 3 rings (3 people, economical consumption, loam soil)
  • 3.2 m2 + 2.5 m2 + 2.5 m2 + 2.5 m2 + 2.5 m2 = 13.2 m2 (>12.8 m2) – 5 rings (3 people, average consumption, loam soil)
  • 3.2m2+2.5m2+2.5m2+2.5m2+2.5m2+2.5m2+2.5m2 = 18.2 m2 (~18.8 m2) – 7 rings (3 people, maximum flow, soil loam)

We also take into account that this is the number of working rings; there will be another ring on top, as in the case of a septic tank. We get 4, 6 and 8 rings, respectively, for the constructed filter well.

We remember the rule according to which the maximum working depth of a septic tank is 2.5 meters. This means that in the second and third options, the filter well needs to be divided into TWO wells. In the case of average flow, we get 2 shafts of 3 and 4 rings. In the case of maximum flow, we have 2 shafts of 4 and 5 rings.

Well, here are our results:

Given: 3 people, economical consumption, loam soil, low groundwater level.

Result: treatment facilities consisting of a 3-ring septic tank and a 4-ring filter well.

The cost of installation is approximately ~ 44,500 rubles.

Given: 3 people, average consumption, loam soil, low groundwater level.

Result: treatment facilities consisting of a septic tank with 3 rings and two filter wells with 4 and 3 rings.

The cost of installation is approximately ~ 65,000 rubles.

Given: 3 people, maximum flow, loam soil, low groundwater level.

Result: treatment facilities consisting of a septic tank with 4 rings and two filter wells with 5 and 4 rings.

The cost of installation is approximately ~ 78,500 rubles.

Calculating a septic tank for a private house is not that complicated, but in any case it is individual for EACH SPECIFIC CASE. Only individual and correct calculation will give you a cleaning system that will work and not require frequent cleaning.

The arrangement of an autonomous sewer system, which is independent of the centralized city one due to its remoteness, is a very troublesome and time-consuming task. These types of sewer systems are installed for dachas, country houses or cottages.

Typically systems include points plumbing equipment for the direct discharge of sewage or household waste, a sewer pipeline that runs from discharge points located in the house goes into a pipeline running underground outside the house and, of course, a septic tank that receives and treats the wastewater.

The main preparatory work before installing an autonomous sewer system is correct calculations septic tank If they are not done, the sewer system may often fail during operation.

The tasks of calculating the required volume and parameters of a particular septic tank involve not only determining and finding the volumes and dimensions of the chambers, but also identifying the amount of building materials, necessary tools or installation equipment.

Therefore, in order to know exactly what parameters need to be purchased or constructed for a septic tank, what building materials may be needed, and in what quantities they are needed, you should correctly calculate the following important details:

  • dimensions of the body and containers of the factory septic tank;
  • daily volumes of wastewater that the septic tank chambers can receive and process;
  • calculations of the volumes of water used per day, which falls on each permanent resident in the house;
  • calculations of the amount of building materials for installation and construction of a septic tank with your own hands.

To ensure sanitation and maintain cleanliness ecological environment any options for septic tanks, both factory-made and home-made, should be installed after you already know exactly the parameters, dimensions of the chambers and its operational capabilities.

Important! And, of course, this must be done long before you decide to buy a ready-made septic tank from one manufacturer or another, and also before you prepare building materials for construction.

You should take into account not only the number of permanent or seasonal residents, but also your income, i.e. the funds you have to arrange your sewer system one type of septic tank or another.

If you want to install a septic tank at your dacha, where you don’t visit very often, then you can get by with homemade septic tank from brickwork, concrete rings or tires, if you don’t have a lot of money.

If you need to install a septic tank for permanent residence V country house, then, of course, it is best to purchase a factory-made septic tank from a manufacturer that has proven itself in the production of high-quality sewerage treatment equipment.

In any case, no matter what kind of treatment facility such as a septic tank has to serve the house, you need to decide in advance on its parameters and volumes, which requires making the appropriate calculations.

How to determine the correct sizes

The key dimensions of a septic tank include such parameters as the length, width and height of the entire structure or the building separately.

To understand exactly what dimensions it is necessary to dig a pit for installing a septic tank, you need to take into account the dimensions of its entire structure, along with pipes, compressors or high necks for maintenance.

And in order to determine the volume of wastewater that the septic tank will need to process per day, it is enough to pay attention to the dimensions of only the body or individual containers, depending on the model design of the treatment plant.

If we're talking about about a septic tank with a solid structure, inside of which there are several chambers, then, roughly speaking, you can estimate its dimensions, which are indicated in its technical documentation, and then compare it with the dimensions of your personal plot.

After all, the installation of such a miracle of sewer technology as must always comply with the standards and requirements of SNiP 2.04.03-85, and this also means the need to maintain legal distances from a residential building to a septic tank, from a drinking well, garden trees to a septic tank, etc.

That is why it is very important to understand how much land you have on your plot, what it is, compare these dimensions and see whether in your conditions it is possible to install a septic tank at certain permitted distances:

  • from the house to the septic tank - at least 5 m;
  • from a drinking well to a septic tank in loamy and clay soils with low soil filtration - at least 25-30 m;
  • from the drinking well to the septic tank with sandy and crushed stone soils with high soil filtration - at least 45-50 m;
  • from garden trees and shrubs to the septic tank to avoid rotting of tree roots - at least 3-5 meters;
  • from the border of the neighboring plot to the septic tank - at least 2 m;
  • from the access roads to the septic tank served by a sewer truck - no more than 3-4 m;
  • from the road often highways to the septic tank without pumping using a sewer truck, in order to avoid soil mobility under the influence of vibration from the movement of machines - at least 5-10 m.

It is all these rules and regulations that should be taken into account when planning and designing the installation of a septic tank on your territory country house, cottage or dacha.

And if garden area yours is not that big, but you urgently need to install a septic tank, that’s when calculating the size of a particular treatment plant will come in handy.

In order to correctly make calculations for future sewer treatment equipment, they most often use septic tank calculation tables specially developed by engineers and designers.

So, for example, a table of daily water consumption rates per person in a particular residential building (temporary or permanent) or average daily water consumption rates per person at any public enterprises or organizations may be useful:


Photo: average daily water consumption per person

It should also be taken into account that the working depth of the sewage treatment plant should not be less than 1.3 m. The width and length should not be less than 1 m.

This is the most optimal parameters septic tank for 1-2 people. The depth from the surface of the earth to the bottom of the septic tank should be no more than 3.2 m, this applies to those treatment structures that are serviced by a cesspool machine.

For other sewer structures, this depth is not significantly important. Especially if you yourself, with the help drain pump clean your septic tank.

Paying attention to dimensions septic tank, its length, width and height, you essentially pay attention to its volume.

We count the volume

To most accurately calculate the volume of a particular septic tank, you can use a very standard formula for calculating the volume of a septic tank:

W– the full estimated volume of the future septic tank in cubic meters(m3);
t– time of sludge processing or storage per day (days);
C– indicator of the concentration of suspended solids at the outlet of the septic tank in milligrams per 1 liter (mg/l);
N– the norm allotted per person per day (l/day);
T– temperature of liquid waste (˚С);
Q– estimated waste flow sewer water in cubic meters per day (m3/day).

As for the temperature of sewer liquids discharged into a septic tank, you need to understand that it will always be different because different plumbing fixtures are used in a house or any enterprise.

But it is generally accepted to take the average temperature as 10˚С in winter, and 15-20˚С in summer. This significantly simplifies the task of calculating volume within the framework of this formula.

Also, in order to determine the rate or estimated period for sewage treatment, simply put, the productivity of the septic tank for the year, experts also use a table for determining the estimated volume:


Photo: table for determining the estimated volume

It is this table that is used when calculating the total estimated volume of a septic tank using the formula:

W = K x Q, where

TO– the estimated period of wastewater settling, which is taken from the table;
Q– daily wastewater flow.

For a more simplified version of calculating the volume of a septic tank, use a simple scheme:

Number of people living X 200 liters of daily average per person X 3 days (wastewater processing time) / 1000 = cubic meters.

But this is a preliminary calculation. The resulting values ​​may fluctuate depending on the number of people who may be added unplanned, for example, guests have arrived or another tenant has appeared.

The volume of water consumed can also change a lot, especially if it exceeds the norm. So, if, for example, a child is born in the house, this may mean that water consumption will increase.

By number of residents

Calculating the volume parameters of the future septic tank that you want to install in your dacha or in the garden of a country house also includes the number of people living.

Tables can also be used to determine the number of people and the septic tank service for the autonomous sewage system of the housing where these people live.

One of them includes a table of general parameters of the useful volume of a septic tank, which must be taken into account when calculating:


Photo: table of general parameters of the useful volume of a septic tank

The useful volume can help to navigate when choosing a septic tank when the buyer sees the parameters of a particular model.

The useful volume can be equated to such a septic tank parameter as productivity or simply the volume of wastewater processed by the septic tank. This is how sewage treatment plant manufacturers usually prescribe this parameter.

The useful volume of a septic tank is calculated based on three times the water consumption per person per day. This is on average 200 l/day.

Therefore, when calculating the volume of a septic tank by the number of people, we see that the average daily norm can be multiplied by the number of people and we will get indicators that will help us choose one or another septic tank.


Photo: septic tank indicators

How to calculate materials for building a septic tank with your own hands

Anyone who is planning to make a septic tank for a country house or cottage with their own hands understands that it is necessary to initially make correct and accurate calculations of the building materials required for installation.

The list of building materials includes not only septic tank containers, but also materials for the manufacture of reinforced concrete or concrete solutions for arranging a foundation-cushion for a septic tank, cement mortars for bricklaying, for example, as well as sprinkling the walls of a treatment plant.

In addition, no matter what kind of septic tank you are going to build from tires or fill a pit with concrete, in any of these cases you will need to know how much sand, crushed stone and cement you need to purchase for construction.

Important! In order to avoid serious mistakes, and subsequently emergency situations in areas of your autonomous sewer system, you must be guided by generally accepted norms and rules during the construction and installation of any structures, including sewage treatment plants.

Thus, the most basic regulatory document, where you can see the correct cement consumption rates for different types of mortars, is SNiP 82-02-95 “Federal (standard) elementary standards for cement consumption in the manufacture of concrete and reinforced concrete products and structures”

Calculations and standards for the construction of a septic tank from reinforced concrete rings and a concrete septic tank

For the construction of a septic tank from reinforced concrete (reinforced concrete) rings, standard iron is usually used concrete rings. Most often, 3 rings are used, each of which has a diameter of 1.5 meters and a height of 0.9 meters.

The resulting volume of such a septic tank also includes the “dead” volume of the treatment plant space, which is located above the level of the outlet pipe through which treated wastewater is discharged into the ground from the septic tank or onto filtration fields.


Photo: septic tank made of reinforced concrete rings

In addition to reinforced concrete rings, a slab covering the entire diameter is also required for the construction of a treatment plant. sewer tank and one cast-iron hatch that protects the septic tank from unnecessary filling with precipitation or storm drains.

Important! In addition, it is necessary to take into account the ventilation system, for which a piece of asbestos-cement pipe with a length of at least 1.5 m, part of which should rise above the ground surface by at least 60 cm, is quite suitable.

In order to install reinforced concrete rings, it will also be necessary to take care of the use of additional and main lifting equipment.

To do this, as a rule, they rent a crane or a winch using automated mechanisms and install reinforced concrete rings one on top of the other. Of course, when installing rings, labor is also required because the work is quite labor-intensive.

Therefore, installers of at least 4-6 people are needed. However, before installation, you should make a cushion and a slab of concrete casting so that the rings installed one on top of the other do not “go” underground under the weight of the entire structure.

Another reason for the mandatory presence of a reinforced concrete platform for the installation of reinforced concrete rings is the very technology of operation of septic chambers, which operate on the principle of a septic tank, which means that the septic tank containers must be sealed.

To form concrete mixtures for pouring the base for installing a septic tank, you need to use the correct and precise proportions to obtain a mixture with good adhesion and strength.

If we assume that ShP-300 grade cement is often used for these construction works, then looking at the table of proportions for the workpiece cement mortar, it becomes clear how much crushed stone and sand you need to take in addition to dry cement.


Photo: table of proportions

However, in addition to preparing building materials in dry form, we all understand that these substances must be dissolved in water to obtain the correct consistency.

Therefore, in order to clearly determine how much water needs to be used for mixing a particular type of solution, specialists often use a summary table of water consumption for mixing concrete solutions.

Using the table, you can determine the type of solution you need, as well as the use of a certain amount of water. So, for example, to make concrete mortar it is not necessary to use a plastic or medium-plastic type of batch.

These types of solutions are more suitable for plastering works. In the case of installing reinforced concrete rings on a concrete site, it is enough to make a low-plasticity or non-plastic concrete solution, and how much water is needed for this can be seen from the table.


Photo: water consumption table

If you summarize the amount of building materials for building a septic tank from reinforced concrete rings with your own hands, you can try to get a complete picture of how much materials you need to spend to install a sewerage treatment plant:

  • concrete rings – 3 pcs. (if necessary, increase the volume of the septic tank and deepen it, use a larger number of rings, but not more than 5 pieces);
  • concrete ring with a bottom or a separate bottom for sewer well– taken according to the number of wells or septic tanks, if it is impossible to acquire a bottom. You can make a concrete pad yourself crushed stone cushion for installation of concrete rings;
  • concrete ring with holes or mesh reinforced concrete rings - such rings are used for the construction of drainage or filtration wells if the septic tank must consist of two or three chambers;
  • floor slab – 1 pc. (if your septic tank is two-chamber, then you will need two floor slabs);
  • ventilation pipe – 1 pc. no less than 1-1.5 meters long (use pipes made of asbestos-cement, metal or plastic);
  • cast iron hatch – 1 pc. (some people prefer to use plastic hatches);
  • cement, sand and crushed stone - the required amount of cement in kilograms can be seen in the table, which shows the amount of dry cement mixture per amount of sand and crushed stone, when using a certain brand of cement - Portland cement:

Photo: amount of dry cement mixture per amount of sand and crushed stone

Other types of cement are used in the following quantities:

  • brand “M – 100” – 166 kg;
  • brand “M – 150” – 205 kg;
  • brand “M – 200” – 241 kg;
  • brand “M – 250” – 300 kg;
  • brand “M – 300” – 319 kg;
  • brand “M – 400” – 417 kg;
  • brand “M – 450” – 469 kg.

If you use cement in bags, which is much more convenient in every sense, each bag is, for example, 50 kg, then calculating the required number of bags of cement for construction work will not be difficult for you.

Concrete mixture hardening accelerators - if you need cement to harden quickly under certain weather conditions, then you should be guided by tables that show the hardening time of different cement mortars.

At certain temperatures, normal hardening and subsequent operation for the strength of certain concrete surfaces or layers.

Also the use of accelerator mixtures, which not only reduce the hardening time of the concrete mixture, but also increase its strength.

Curing table concrete mixtures when using certain grades of cement or concrete:


Photo: table of hardening of concrete mixtures

Table of accelerator mixtures for hardening concrete solutions:


Photo: table of accelerator mixtures for hardening concrete solutions

Sealing materials - after installing reinforced concrete rings, they must be properly sealed. This is done not only by plastering the seams between the rings with cement mortar.

But also by applying absorbent materials to the entire surface, which provide reinforced concrete surfaces reliable waterproofing for many years.

To do this, use dry mixtures, which are diluted according to the instructions and applied to the surface of concrete rings from the outside and inside. Such mixtures include: trade marks: “Bastion”, “Tekmadray”, “Penetrat” and others.

But you can waterproof and polyethylene films, roofing felt and other rolled creeping materials.

Tools, equipment and machinery - do not forget also about the tools and equipment for construction work on the installation of concrete rings for a sewage treatment plant:

  • lifting equipment is a mandatory attribute of construction work for the installation of concrete rings;
  • workforce – at least 4-6 people;
  • concrete mixers - you can use a device with an electric drive, or you can get by with a metal box or tin sheet with parameters of 1.5 x 1.5 m;
  • buckets - they are necessary for transportation across construction site bulk building materials;
  • wheelbarrow with a metal body - for moving ready-made concrete or cement mortars;
  • shovel - for laying concrete solutions during construction work;
  • cutting tools for concrete - hammer drills or grinders with certain attachments, which allow making holes in concrete rings for laying and supplying sewer pipes.

Plastic or cast iron sewer pipes– they must be connected to the septic tank and reliably sealed with construction silicone or sealant.

Wood for casting formwork concrete walls– to cast a septic tank from concrete, you will need to build not only a concrete pad, but also cast concrete walls, for which wooden boards are used to install the formwork into which concrete is poured.

Important! Also, do not forget that if your septic tank is designed to serve not only the sewer system of the house, but also storm or drainage, then when connecting sewer pipelines to the septic tank, be sure to also use tees, adapters, turn signals or differential wells.

It all depends on how relief your soil conditions turn out to be and the required slopes for arranging a gravity sewer.

To install a septic tank from concrete walls by pouring concrete into the formwork, you should also use the above tables for the production of concrete mixtures, taking into account all the necessary proportions.

Calculations used and required standards for installing a septic tank from tires

The cheapest or, as experts say, budget option Installation of a septic tank at the dacha is the construction of a septic tank from tires.

Or country cottage, cottage or small mansion also provides such a simple option as installing a septic tank from tires.

This method is used in cases where there is an urgent need to arrange a sewer system, and for this they use a makeshift septic tank made from tires. However, this type of construction only seems simple.

In fact, certain calculations are also required here in order to build a sewer system that works without failures or interference.


Photo: septic tank made from tires

Regardless of the exact sizes of tires you will use, to calculate the volume of the future septic tank from old car tires, you can use the generally accepted formula:

V = π r2h

Where:
V– volume of all septic tank designs,
π – constant value (3.14),
r2– radius of a particular tire,
h– the height of one old tire.

Now you need to decide on the volume of wastewater that will flow into the septic tank, and which it will have to not only accept, but also process.

For these calculations, use the daily rate of water consumption per person, which is indicated in SNiP 2.04.09-85:

  • minimum – 125 l/day;
  • on average 200 l/day;
  • maximum – 270-350 l/day.

Then this figure must be multiplied by 3 days, the amount of time for processing and settling of accepted sewage liquids, and the resulting figure must be compared with the resulting volume of the septic tank itself.

If these numbers are close or coincide, it means that you have correctly calculated the volumes, and your septic tank will serve you for decades.

Important! In addition to determining the number of tires to create the required volume of the septic tank chamber, you should also calculate the amount of cement, sand and crushed stone used.

To do this, you can use the same tables that were given for calculating a septic tank made of concrete rings.

The entire process of pouring the foundation for a septic tank, as well as sprinkling it, is carried out almost the same for all types of installation of treatment facilities.

Made of brick

For construction it is also necessary to know approximate or even exact amount bricks, bulk building materials, floors, hatches and what is necessary for the construction ventilation device in a brick treatment plant.

First of all, it should be said that brick two-chamber septic tanks must have a concrete base slab on a crushed stone base. This must be done for the strength and reliability of the entire structure.


Photo: foundation diagram

Very good option manufacturing such a base is a method of a reinforced concrete platform with a built-in drainage system.

This design allows for unimpeded standing sewerage, while not coming into contact with groundwater or melt water.

After all, built inside a crushed stone cushion drainage pipes will easily be taken away excess water from the septic tank to avoid accidental entry of excess groundwater into the septic tank.

In addition, a layer of waterproofing film will reliably protect any septic tank structure from overflow or flooding.

In order to determine the required amount of brick for a particular size of your septic tank, you can use a table specially developed by technologists, which will tell you required quantity bricks for building a septic tank according to exactly the parameters that your sewer system needs:


Photo: number of bricks for building a septic tank

Also, we should not forget about the breakage of brick building materials. Typically, specialists in the installation of brick septic tanks take the generally accepted percentage of broken bricks - 5% of the total amount required quantity bricks, which you calculated using the table.

This 5% must be added to total number brick, so you will receive the required amount of brick building material for installing your septic tank.

As is known, construction brick walls always occurs by laying bricks on cement mortar.

Therefore, it is necessary to determine what kind of mortar should be made specifically for laying bricks and plaster on bricks. Brick is considered a looser material than concrete rings, and therefore absorbs much more moisture.

Therefore, the mortar for bricks is made a little differently, and exactly how you can understand it by first studying the table of mortars for brickwork:


Photo: table of mortars for brickwork

If you lay bricks in the cold season, then the time for the joint mortar to harden will increase.

To speed up the process of adhesion of bricks to cement mortar, saline solution or simply salt is often added to the mixture in the approximate proportion of 1.5 packs of salt per batch of cement mortar in a ratio of 1:3 or 1:4 (cement: sand).

And if you want to improve adhesion and drying speed, use detergent, which is also noted by experts as effective method acceleration of hardening by brickwork, then apply the following proportion: 200 liters of water to 0.5 liters of any detergent.


Photo: brick septic tank

Modern technologies in the field of construction have gone much further than folk remedies manufacturing masonry mortars for brick walls.

Today, the modern building materials market offers a fairly wide range of masonry materials. ready-made mixtures, intended for use in bricklaying of any brand and size.

Important! This fact is also worth paying special attention to. All proportions for mixing such mixtures are always indicated on the packaging by the manufacturers, and therefore it will not be difficult for you to calculate how many bags or packages you will need for laying the brick walls of a septic tank.

Example: calculating a septic tank for a family of 4 people

For example, you can consider the option of calculating a septic tank for servicing a house where 4 people permanently live.

0.8 x t x (100% - 30% / 100%) x 120% = 0.8 x t x 0.7 x 1.2 = t x 0.672 sec.

0.8 – consumption of the solid residue of processed waste, calculated per person;
t– time of rotting of solid residues in days;
100% — total volume of sludge;
30% — percentage of natural decomposition of sludge;
120% — 100% total volume of sludge + 20% of sludge residues from the previous cleaning of the septic tank.

To take a closer look at calculating water consumption per person per day, you should first determine the amount of use of plumbing equipment, as well as the frequency of use of plumbing equipment in the house.


Photo: amount of use of plumbing equipment

For calculations per person, let’s take a minimum water consumption of 150 l/day.

So, for example, the average consumption and consumption of water by one person can make up the following picture:

  • one minute of taking a shower will consume about 10 liters of water;
  • taking a shower or bath takes about 7-15 minutes on average;
  • when using a bidet or toilet, water consumption is about 8 liters;
  • Using a bidet takes an average of 5 minutes;
  • One bath or jacuzzi requires 110 liters of water;
  • a washing machine with a load of 2 kg of laundry consumes 70 liters of water per wash;
  • A dishwasher spends 15 liters of water during one cycle of operation.

(150 + 10 x 7 + 8 x 5 + 110) = 370 l/day.

Thus, from the minimum daily water consumption by one person, we reached the maximum daily water consumption by one person – 370 l/day.

Both indicators, minimum and maximum, are indicated in SNiP 2.04.09-85, which indicates the correctness of the calculations.

Now let’s calculate the total consumption (Q) for water consumption, including washing and dishwasher, for 4 people permanently residing in the house:

Q = 370 x 4 + 70 + 15 = 1565 = 1.6 cubic meters per day

Considering the previous formula for calculating the volume of a septic tank - 3 x Q, we can now calculate the volume of a septic tank to serve a family of 4 people:

3 x 1.6 = 4.8 m3

4.8 m3 in this situation is the most optimal indicator for calculating the volume and size of the septic tank. If you need to take into account the minimum size of the septic tank, then you can use the following calculations:

4.8 x (1-0.2) = 3.84 m3

This must be done in cases where it is necessary to reduce the size of the septic tank to its minimum use when there are 4 permanent residents.

The reduction calculation formula only uses permissible norm wastewater treatment is 20% less, it cannot be reduced any more.

If this assumption is violated, emergency flooding of the septic tank, soil poisoning and environment and, as a consequence, the imposition of high fines government agencies. Who will have every right to do so.

To calculate the required depth for the construction of a particular septic tank, which will have to serve a family of 4 people, you can use the following standard calculations:

4.8 / 1 / 1.8 – 2.6 meters, where

4,8 – cubic meters of septic tank volume;
1 – meter width of the septic tank;
1,8 - meters along the length of the septic tank.

This measure may be necessary if your personal plot limited in area, and you cannot give up a lot of land for the development of a septic tank.

In some regions of Russia, the depth of soil freezing is about 2 meters or more.

Any violation or deviation from the norms and rules adopted in the state documentation SNiP leads, as a rule, to a complete stop in the operation of a particular septic tank, as well as to the imposition and payment of penalties in large sizes provided for by the legislation of the Russian Federation.

Important! Therefore, before constructing or installing finished treatment equipment, it is necessary to clearly monitor all the rules and regulations for the installation of autonomous sewers, which can be found, first of all, in SNiP 2.04.03-85 “Sewerage.

External networks and structures" and others regulatory documents. It is also necessary to do whole line correct and accurate calculations of the volume of water consumption, the volume of the septic tank, its design and installation parameters.

It is worth noting that today there is a large number of types of septic tanks. They all differ in size, principle of operation, material of manufacture and cost.

The most simple designs you can make it yourself. And the first thing you need to know is the optimal volume of the septic tank.

Why is this necessary? If the volume is too small, the system will not be able to cope with the processing of wastewater; if it is too large, you will simply spend extra money and effort on arrangement.

Calculation of the size and volume of a septic tank

Formula

And in order to solve the problem correctly, you should use one simple formula.

It looks like this: V=n*Q*3/1000, where:

  • V – total volume of the septic tank in cubic meters;
  • n – number of people permanently residing in the house;
  • Q is the volume of water consumed by one person per day;
  • 3 is the number of days required to treat wastewater. It is regulated by SNiP.

Volume calculation

That is, in order to calculate the septic tank, we just need to multiply three indicators: the number of residents of the house, the volume of water consumed, the duration of the wastewater treatment cycle.

You should also take into account situations where water consumption may increase, for example, if guests come to the house for a long time or all household members are at home and actively use the sewer system. For such cases, you need to leave a reserve.

Usually, the result obtained during the calculations is simply multiplied by a factor of 1.2.

In order to calculate the volume of a septic tank correctly, you need to take into account some additional points.

For example, you can find information that one person uses no more than 150 liters of water per day.

By the way, if you need to calculate a septic tank for a private house equipped with all modern amenities, you need to know the following:

  • taking a shower on average costs 70 liters if its duration is 7 minutes;
  • using a bidet for 5 minutes requires wasting 40 liters of water;
  • one bath or jacuzzi will require about 110 liters of water;
  • a dishwasher will spend about 15 liters per cycle.

Septic tank for three people

If all this equipment is present in the house, then the calculations will be made somewhat differently.

The first three points will be calculated for one family member. This gives the formula: Q=150+70+40+110.

It turns out that there will be 370 liters of water per person per day.

Calculation examples

Then the formula will look like this: V=370*3+70+15=1195 liters or 1.2 m3.

Considering the fact that wastewater is processed within three days, the resulting figure should be multiplied by 3. The result will be 3.6 m 3.

You can also use it to calculate the volume of a septic tank.

Formula for calculating the volume of septic tanks

If we calculate the volume of a septic tank for a private house where 5 people live, we get the following formula: V=370*5+70+15=1935 liters or 1.9 m3.

Then the total volume of the septic tank will be 5.7 m3.

It is important to understand here that if the total volume of wastewater does not exceed 5 cubic meters, you can get by with a single-chamber septic tank. But, if the figure obtained as a result of calculations is larger, it is worth equipping a two- or three-chamber septic tank.

For a two-chamber septic tank, the volume of the first tank will be equal to 75% of the total calculated volume, and the second tank will be 50% of the same figure.

The volume of chambers in a three-chamber septic tank will be 50%, 25% and 25%, respectively. Having figured out how to calculate the volume of a septic tank, you should determine its optimal dimensions.

There are standards and a special formula for this.

Determining the size of a septic tank

If you need to determine the size of a septic tank, it is worth remembering that the surface area of ​​the container cannot be less than 1.8 square meters.

So for a container with a volume of 3.6 m 3 the depth will be 2 meters. She's getting it simple method counts: 3.6/1/1.8.

To connect plumbing fixtures to the water supply network, a flexible water supply is used. It is in demand when connecting faucets, showers, toilets and other water intake points, and significantly simplifies the installation process. Flexible eyeliner also used during installation gas equipment. It differs from similar water devices in its manufacturing technology and special safety requirements.

Characteristics and types

The flexible hose for connecting plumbing is a hose of different lengths made of non-toxic synthetic rubber. Thanks to the elasticity and softness of the material, it easily takes the desired position and allows installation in hard to reach places. To protect the flexible hose, there is an upper reinforcing layer in the form of a braid, which is made from the following materials:

  • Aluminum. Such models can withstand no more than +80 °C and retain functionality for 3 years. At high humidity Aluminum braiding is prone to rust.
  • Of stainless steel. Thanks to this reinforcing layer, the service life of the flexible water line is at least 10 years, and Maximum temperature transported medium - +95 °C.
  • Nylon. This braid is used for the manufacture of reinforced models that can withstand temperatures up to +110 °C and are designed for intensive use for 15 years.

The fasteners used are nut-nut and nut-fitting pairs, which are made of brass or of stainless steel. Devices with different indicators permissible temperature differ in the color of the braid. Blue ones are used for connecting to a pipeline with cold water, and red ones - with hot ones.

When choosing a water line, you need to pay attention to its elasticity, reliability of fasteners and purpose. It is also mandatory to have a certificate that prevents the rubber from releasing toxic components during operation.

Features of gas connections

When connected gas stoves, speakers and other types of equipment also use flexible hoses. Unlike models for water, they have yellow and are not tested for environmental safety. For fixation, end steel or aluminum reinforcement is used. There are the following types of devices for connecting gas appliances:

  • PVC hoses reinforced with polyester thread;
  • made of synthetic rubber with stainless steel braid;
  • bellows, made in the form of a corrugated stainless steel tube.

Santekhkomplekt holding offers engineering equipment, fittings, plumbing and devices for connecting it to communications. The assortment is represented by products and materials from well-known foreign and domestic manufacturers. Discounts apply for bulk purchases, and product quality is confirmed by standard certificates. For information support and assistance, each client is assigned a personal manager. The ability to arrange delivery within Moscow and to other regions of the Russian Federation allows you to quickly receive the purchased goods without unnecessary hassle.

Drainage is a drainage and drainage measure to remove excess groundwater.

If water does not leave the site for a long time, the soil becomes gleyed, if shrubs and trees quickly disappear (get wet), you need to urgently take action and drain the site.

Causes of soil waterlogging

There are several reasons for soil waterlogging:

  • clay heavy soil structure with poor water permeability;
  • aquifer in the form of gray-green and red-brown clays is located close to the surface;
  • high groundwater table;
  • technogenic factors (construction of roads, pipelines, various objects) that interfere with natural drainage;
  • disruption of the water balance by the construction of irrigation systems;
  • The landscape area is located in a lowland, ravine, or hollow. In this case, precipitation and the influx of water from higher places play a big role.

What are the consequences of excess moisture in the soil?

You can see the results of this phenomenon yourself - trees and shrubs die. Why is this happening?

  • the oxygen content in the soil decreases and the carbon dioxide content increases, which leads to disruption of air exchange processes, water regime and nutritional regime in the soil;
  • oxygen starvation of the root-forming layer occurs, which leads to the death of plant roots;
  • the supply of macro and microelements by plants (nitrogen, phosphorus, potassium, etc.) is disrupted, because excess water washes out mobile forms of elements from the soil, and they become unavailable for absorption;
  • intensive breakdown of proteins occurs and, accordingly, the processes of decay are activated.

Plants can tell you at what level groundwater lies

Take a close look at the flora of your area. The species inhabiting it will tell you at what depth the ground water layers are located:

  • perched water - it is best to dig a reservoir in this place;
  • at a depth of up to 0.5 m - marigold, horsetails, varieties of sedges grow - bladderwrack, holly, foxweed, Langsdorff's reed;
  • at a depth of 0.5 m to 1 m - meadowsweet, canary grass, ;
  • from 1 m to 1.5 m – favorable conditions for meadow fescue, bluegrass, mouse pea, china;
  • from 1.5 m - wheatgrass, clover, wormwood, plantain.

What is important to know when planning site drainage

Each group of plants has its own moisture needs:

  • at a groundwater depth of 0.5 to 1 m they can grow on raised beds vegetables and annual flowers;
  • water depth up to 1.5 m is well tolerated vegetable crops, cereals, annuals and perennials (flowers), ornamental and fruit and berry bushes, trees on a dwarf rootstock;
  • if the groundwater is more than 2 m deep, fruit trees can be grown;
  • optimal depth of groundwater for Agriculture– from 3.5 m.

Is site drainage necessary?

Record your observations for at least some time. You yourself can understand how much drainage is needed.

Maybe it makes sense to simply redirect melt and sediment water along the bypass channel, rather than allowing it to flow through your site?

Perhaps it is necessary to design and equip a storm drain and improve the composition of the soil and this will be enough?

Or is it worth doing drainage system only for fruit and ornamental trees?

A specialist will give you the exact answer, and we strongly recommend calling him. But after reading this article, you will gain some awareness on this issue.

Upon completion of technological and production tasks related to the arrangement of the sewer system in apartment building, industrial building, and also in private households it is required to test the involved system using the forced flow method. This task is used to identify possible defects or improper installation of the entire involved sewerage part, and the test report for internal sewerage and drainage systems will be material evidence of the work on acceptance of the facility.

A visual inspection should be accompanied by inclusion in the test report of internal sewerage and drainage systems according to SNIP, which is currently represented by the current regulations of the “D” series appendix, which corresponds to SP 73.13330.2012 “Internal sanitary systems of a building”, in Lately the new updated working edition according to SNiP 3.05.01-85 is applicable.

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

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

Calculation of septic tank volume.

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

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

Please note: sanitary standards indicate that the discharge of water from a septic tank into the soil (into a drainage well) should occur no earlier than 14 days from the moment it enters the septic tank. Those. settling of water and its purification by anaerobic bacteria in a septic tank should take place for at least two weeks.

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

It should be noted that the wastewater flow rate of 200 l/person per day specified in SNIP is not always achieved in practice. With economical use of water, which is becoming typical for a private house, the volume of wastewater will be more likely 0.1 m3. per day (100 liters) per person. Then the septic tank is “very economical” and does not meet the requirements of the standards (may be rejected by the sanitary services), but nevertheless works for 4 people, maybe 1.5 cubic meters. But this, again, for your information, such septic tanks cannot be built.

Savings during construction are not always profitable. The wastewater is full of substances that are difficult to process by anaerobic bacteria or are not processed at all. First of all, these are heavy fats. It is important to construct treatment facilities in such a way that sufficient clarification of the water occurs in the septic tank. So that heavy substances and fat would settle to the bottom and be processed or removed later in the form of sediment by a sewage disposal machine.

Increasing the volume of the septic tank will always have a positive effect on the quality of water treatment and its maintenance.

The owner of the site is very interested in ensuring that the most purified water flows from the septic tank to the drainage well or to the aeration fields. If heavy impurities (fats) remain in the water, the filter layers will very quickly become silted, clogged with difficult-to-decompose fat, and lose their throughput. This will entail very big problems– reworking the entire accumulation and filtration system.

Therefore, irresponsible reduction of septic tank volumes is not acceptable at all.

Number of cameras

When choosing the volume of the chamber and their quantity, you also need to take into account the tank volume of a small sewer truck - 3.75 cubic meters. And also the operating depth of the suction pump is up to 3 meters. The working volume and depth of the first chamber should not exceed these values.

In principle, increasing the number of chambers has less effect on the quality of purification than the entire volume of the septic tank. The residence time of the waste is important - at least 3 days. As well as the composition of the water leaving the septic tank.
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Consequently, to achieve the minimum volume of a septic tank for an “average” house of 2.7 cubic meters. it is also possible with a single-chamber septic tank (for example, this volume is achieved by two reinforced concrete rings with a diameter of 1.5 m).

But if you remember the recommendations sanitary standards, and the issue of preserving the soil and environment near the house, as well as the fact that wastewater can be “difficult,” especially when operating washing equipment and an extra 1 - 2 days of settling is necessary, then of course it is better to increase the volume, improve the quality of wastewater, and of course use a two-chamber septic tank, even for this case.

Single chamber treatment plant with filtration through the bottom (essentially -), according to the standards, can be done only with a very small flow, when the sewerage system is used only occasionally at the dacha.

Which design option to choose

Let's consider the most common designs of septic tanks - made of reinforced concrete rings.

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

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

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

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

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

Please note that all pipes entering the septic tank must end with fittings pointing downwards and open at the top - tees. This will prevent floating debris and fatty films from overflowing, correctly direct the flow of liquid, and provide ventilation. Manholes into the septic tank are equipped opposite the inlet tee

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