Absorption area drainage trench more, but in clay soils will have to dig the entire garden. When I needed to pit, I decided that using the scheme of the septic tank. First of all because it's cheaper than any ready-made solution and does not require electricity to operate. Calculation of the volume produced in this way. The maximum water consumption for a family of three 1200 liters per day. There is a perception that water for effective cleaning of septic tanks should be about two days, then the working volume of the septic tank must be at least 3.6 m3.
With Taj-Euro-system has been prepared hole with a diameter of 1.6 m depth of 4 meters, which were installed four concrete ring with a diameter of 1.5 m and a height of 0.9 m. Release of sewer pipe from the house I was at a depth of 1.2 m. So out, but do correct output at a depth of at least 1.5 m (depth of frost penetration). Septic tank made of concrete rings can be warmed, though are generally assumed that the warm waste water is not frozen. The slope of the pipe should be about 2 cm per meter. Neither the Do not make a big slope, as in this case, a liquid effluent will be merged into the hole faster and more dense deposit on the walls of pipes, which can lead to undesirable consequences, plugging. Given the slope and distance from home, which should not be less than 8 feet, downhill pipe, I was at a depth of 1.5 meters from ground level.