You can use a finished factory concrete product.

A well for filtering

For the construction work of the well, specialized rings from concrete of different diameters can be used, but not less than 1 m., Brick silicate, laughter stone, concrete blocks. There may be an option using car, used, large tires, which when installed, fit one on the other and are fastened with a cable or reinforcement. The depth of the foundation pit for the well is reduced by the level of soil waters. The diameter of the pit must be more than the diameter of the concrete ring by 60 — 80 cm. The bottom of the pit should be concreted so that the contour of the ring, lowered into the pit, relies on a concrete surface, and the center of the pit was not a pouring a solution of cement. Each next ring is placed using a cement mortar. The bottom of the well and the distance between the rings and the walls of the foundation of the foundation of the foundation are sleeping with rubble, brick (waste) or concrete blocks (waste). This protects tightening and clogging with silt holes in the walls made for stack of water. The number of holes is free and will depend on the volume of liquid drained into the sewer. Their diameter 5-8 cm. Pipe for draining, the main from the septic tank, is introduced into the well through the hole made in the ring. The edge of the pipe is obliged to move away from the wall by at least 10 cm to eliminate erosion. The well is covered with a concrete lid with a hole and a hatch for a ventilation pipe. You can use a finished factory concrete product. If the construction of a filter well is unrealistic, the filter channel lays down. Before weching pipes for sewage, from the septic tank in the direction of the structure one or more trenches rummage. They put pipes with a large number of small holes in them. The liquid from the septic tank enters the perforated pipes, from which, having passed the final cleaning, it flows into the soil.