How to Design a Septic Leach Field

Leach field trenches should be at least one foot deep and 20 feet long.

A leach field is the area in which liquids from a septic system are dispersed into the soil. As the liquid seeps into the soil, bacteria remove organic agents, cleaning the solution so it can safely evaporate back into the atmosphere. While building a leach field can be an intensive endeavor, the process is fairly simple.

Things You'll Need

• Gravel
• U-Connector
• 5-foot solid PVC pipe
• Distribution box
• Shovel or spade
• 60 feet of 4-inch diameter perforated piper
• Grass seed

Instructions

1. Connect a distribution box to your septic tank. Connect a four-inch solid pipe to each end of the distribution box. The pipe leading from the distribution box will be connected to a series of pipes that will carry septic liquid to the leach field after it's built.

2. Dig distribution trenches. Three trenches are recommended. Each trench should be at least one foot deep and lead from the distribution box to the leach field. Line the bottom of the trenches with gravel to ensure pipes stay in place. Trenches should be at least 20 feet long and lead to a flat surface away from obstructions such as sheds, driveways and trees.

3. Install distribution plumbing. Attach a U-connector with room for three PVC pipes to the pipe leading from the distribution box. Connect each pipe and lay them in the bed of gravel. Make sure each pipe is taped and secure.

4. Bury the pipes with a second layer of gravel and topsoil. Before covering the pipes with topsoil, cover them with two to three inches of gravel. Gently tamp the topsoil and cover it with straw or natural grass seed.

Tips & Warnings

• Avoid planting trees or other rooted plants in your leach field. Roots can obstruct piping and clog your septic system.

References

• Kitzman's Home Center
• The Natural Home Building Source

Resources

• HHomeowner Manual for Septic Tanks and Leach Fields