Septic tanks are underground tanks where the sewage is collected. These systems can be build in many ways. However, their building is not an easy and quick process. Firstly, the capacity of the tanks is 130 liters to 70 liters per head. After every two years these tanks should be cleaned. Around the tank, there is a brick wall with, and foundation floor from thick cement. Usually, the tanks are round, they do not have corners. Secondly, you should make the tank waterproof. You can use Impermo, Accoproof or Cem-seal.
Septic Tanks Systems and Designs
See the video below. You can see the amazing explanation for these systems.