A drain field distributes the effluent water from a septic tank to the soil, allowing natural purification before it returns to the water tables. Its components include a distribution box, gravel and perforated PVC pipe. It may take days or weeks to complete the process of obtaining permits, digging suitable trenches, laying pipe, installing gravel and backfilling the trench./
In most locations, installation of a drain field requires a permit. Building codes often require that a licensed contractor design and install the drain field, and a soil percolation test to determine the rate at which the soil is able to absorb water.
The design of the system determines the depth and length of the lines. One common design uses three lateral lines, each 100 feet in length and connected to the distribution box. While it is possible to dig these trenches by hand, most owners hire a contractor to dig these trenches.
Check the codes for the size and depth of gravel required. The depth typically ranges from 6 to 12 inches, and the gravel should be larger than the perforations in the pipe. At this point, work often stops, awaiting approval by an inspector. If the system passes inspection, install another 6 to 12 inches of gravel over the pipe.
Fill the trench with soil removed earlier. Plant grass over the drain field to prevent erosion. Do not plant other landscaping over the area.