Calculation of a septic tank for a country house

Owners of summer cottages and country houses try to provide themselves with the most comfortable living conditions. For these purposes, all the necessary engineering networks, including sewerage, are equipped in the houses.

Considering that in most cases it is not possible to connect the wastewater system of a country house to a centralized sewerage network, they organize their own wastewater disposal system on the site in the form of a factory-made septic tank or a self-built one.

Regardless of what type of septic tank is supposed to be used, before its manufacture, it is necessary to make a competent calculation of its useful volume, which is necessary for the disposal of wastewater from a particular house. To do this, you need to know how to calculate the volume of a septic tank.

What is the basis for calculating the volume of a septic tank

This article will provide detailed instructions that will help calculate the minimum allowable useful. As an example, a calculation of the volume of a septic tank from concrete rings for a small family will be presented.

What you need to know to calculate the volume of a septic tank

The most common option for a septic tank is a two- or three-chamber treatment system. It consists of two or three reinforced concrete or plastic containers located next to each other, connected in series with each other using sewer pipes.

Wastewater, as it enters the septic tank, in the first tank is settled from mechanical impurities and slowly flows into the second tank, in which the residual part of the impurities precipitates and biological wastewater treatment takes place.

Bacteria found in the water process organic matter that contains wastewater. After that, purified water is formed, which is fed to the third tank for post-treatment, and from there, already pure water enters the soil or is used to water plants. In the case of a two-chamber system, water from the second tank is supplied to the filtration fields for soil post-treatment.

According to the technology of water purification, for the proper functioning of the purification system, it must contain at one time such an amount of water that will be consumed in the house within three days.

Technology for calculating the minimum required volume of a septic tank

The basic basis for calculating the volume of a septic tank is the total volume of effluents produced by all people living in the house in one day. According to statistics, it is conventionally accepted to consider the average daily water consumption at the rate of 200l. for one person.

Accordingly, for the calculation it is necessary to multiply 200 liters by the number of people living in the house. You can determine the approximate value of the required volume of a home treatment plant from the table below.

Volume calculation table for a two or three chamber wastewater treatment system.

However, the data given in the table are indicative only. The actual value can fluctuate within small limits, both up and down, and depend on many factors.

For example, the presence of a bath or sauna in the house, as well as household appliances that consume a large amount of water, such as a washing machine or dishwasher, can cause a significant increase in water consumption, and, accordingly, an increase in domestic wastewater.

Advice! In the case of connecting a water supply to a centralized water supply system, installing a water meter (in other words, a water meter) will help not only maintain a more economical water consumption mode, but will also reduce the load on the treatment system.

An example of calculating the volume of a septic tank

As a sample, we propose to consider the calculation of the volume for a family of 4 people who permanently live in a country house.

• Based on simple calculations, it can be calculated that the total daily volume of wastewater is 0.8 m³. (0.2 m³ X 4 people = 0.8 m³)
• Taking into account the need to settle wastewater for three days, we obtain the value of the minimum total volume of the septic tank, equal to 2.4 m³. (0.8 m³ X 3 days = 2.4 m³)
• If a two-chamber type treatment plant is planned to be made of standard concrete rings KS 15-9, we take for calculation its internal diameter of 1 m, useful height 0.7 m, we get useful volume = 1.64 m³. Accordingly, two chambers will give a total volume of 3.28 m³.
• From here we see that the value of the total volume of the septic tank is more than the minimum allowable, and gives some more margin, which allows increasing the daily volume of wastewater without overloading the treatment system.

Note! When calculating the useful volume of a concrete ring, it is necessary to take into account not the full height of the ring, but the useful height that the wastewater reaches before overflowing into the next chamber, that is, the height from the base of the ring to the lower edge of the overflow pipe.

Conclusion

As you can see from the article, for the proper organization of a makeshift treatment plant on your site, it is necessary to carry out very simple calculations and follow the rules and recommendations for arranging septic tanks. The price of concrete rings allows you to install such a treatment system at their summer cottage, even for families with a relatively low level of income ().

In the presented video in this article you will find additional information on this topic.