General Contact Number: (530) 621-5567

Environmental Health

Septic Components - Leach Line Trenches

Trenches are long, narrow systems that allow the soil to treat the effluent. The method of distribution is usually gravity (See "Septic Components: Distribution").

The materials used in trenches have changed over the years. Typically, systems have been constructed out of 4" pipe and rock. A number of plastic products have become available recently to replace the rock and gravel-less trenches are becoming more common. (See Septic Components: Leach Lines").

It is important that the bottom of the leach line trench is a minimum of 5 feet from groundwater to prevent contamination.

It is also important that the bottom of the trench is level, allowing for an even flow of effluent. 

Image of inspectors Inspecting grade
Inspecting open trenches
Image of inspectors shooting grade
To determine the level of the trench bottom, this contractor is shooting the grade