A septic tank (in common parlance, a drain or cesspool) is a necessary structure for the improvement of a private estate, estate or country cottage, providing comfortable living in terms of drainage of waste liquid. Its only inconvenience is the need to periodically remove the accumulated contents for further use. However, there is a way to build a unique septic tank with your own hands for your home and dacha - without pumping for 10 years or more, it can receive waste water, allowing owners to freely use water and the toilet. The whole secret is in the features of its device.
The appearance of the finished septic tank does not spoil the overall ambience of the private yard
Calculation of septic tank volume
In general, I did not go much into the theoretical part of calculating a septic tank; I only read some articles by A. Ratnikov, a specialist in the disposal of liquid waste and water supply of country cottages.
According to standards, the volume of a septic tank should be equal to three times the daily influx of wastewater . During this period, bacteria must process this volume of sewage.
The daily norm for one person is 200 liters . From these numbers the entire calculation of the volume of the septic tank is made.
Those. if you have a family of 4 people , calculate the volume of the septic tank: 4*200*3 = 2400 liters (2.4 m3) .
Therefore, when using, for example, well rings (Ks 15-9) (diameter - 1.5 m, volume - 1.59 m3), you will need two such rings when building a single-chamber septic tank . Keep in mind that the volume of the rings is “dirty”, that is, you will not be able to fully use the volume of the upper ring, since it will not be completely filled with waste.
Much also depends on the filtering capacity of your soil and the groundwater level. Septic tanks for dachas with a high groundwater level (GWL) are preferably built at shallow depths and should have a shallow filter well, preferably up to the surface of the groundwater.
If the soil is mainly clay, you need to increase the area of the filtration well several times, because Clay filters water through itself very poorly.
The working depth of the septic tank, equal to the distance from the wastewater level in the septic tank to its bottom, must be at least 1.2 m, width 0.75 m (or diameter 1 m for septic tanks with a round plan). The maximum working depth of wastewater in a septic tank should not exceed 2.5 m.
Principle of operation
Septic tank diagram without pumping
Such a septic tank has several adjacent tanks. In most cases, two and sometimes three chambers are made. The first chamber is intended for a sump. If the septic tank is two-chamber, then the volume of the first chamber will be ¾ of the entire structure. If the structure is three-chamber, then its volume will be equal to half of the total volume of the septic tank.
When wastewater enters the first chamber, it is purified because the heavy fractions settle, and those that flow more easily into the next chamber. The overflow is carried out as the first chamber is filled, and already in the last chamber the liquid is completely purified, which can be used for irrigation or sent to a drainage well.
It is very important that each tank is sealed. Based on the design, small holes must be made in the walls and at the bottom of the last chamber. This will allow you to remove moisture without problems, as well as completely eliminate its accumulation.
Digging a pit for a septic tank
After you have decided on the volume of the septic tank and filtration well, as well as the number of chambers in the septic tank, you need to dig a pit (pit) for it. The fastest way to do this is with an excavator, and if the ground level is low, this is the only digging option, since digging by hand with a shovel in the mud is not very easy
