Approved Pipe Materials

Effluent Sewer Pipe

The effluent sewer pipe is the distribution pipe that extends from the septic tank or gravity discharge point of a sand filter to the distribution box at the beginning of the first absorption trench in the absorption field.

• Minimum inside pipe diameter: Three (3) inches. Four (4) inch diameter pipe is typically installed.
• Pipe minimum fall or gradient: Two (2) inches for pipe runs up to but not exceeding ninety-nine (99) feet. Four (4) inches for each additional one-hundred feet of pipe run thereafter.

Note: A minimum elevation difference of eight (8) inches between the invert of the septic tank outlet and the invert of the solid header pipe extending from the distribution box to the perforated pipe in the first absorption trench is required.

Absorption Field Pipe

The distribution pipe and perforated pipe that is found in the absorption field area of a septic system.

• Minimum inside pipe diameter: Three (3) inches. Four (4) inch diameter pipe is typically installed.

• Pipe minimum fall or gradient: From distribution box to absorption trench perforated pipe: +/- one (1) inch

• Absorption trench perforated pipe: +/- one (1) inch

Note: The perforated pipe in the absorption trench is required to have perforations that are one-half (1/2) inch diameter in size. The perforations must be separated by a minimum separation distance of five (5) inches and configured on the pipe in two (2) rows that are pointed downward and oriented sixty (60) degrees on either side of the pipe centerline.

Pressure Distribution Pipe

The pressure distribution pipe is the pipe that transports effluent discharged from an effluent pump in a septic/dosing tank, dosing septic tank, dosing tank, or a pump basin in a sand filter.

• Minimum inside pipe diameter: 0.75 inch.