About Valve Switching and Low Pressure Pipe Fields

Understanding Low Pressure Pipe Systems

Low pressure pipe systems are also commonly referred to as Bell-Patt or low pressure drip systems. These systems consist of one or more drain fields divided into sections, usually ranging from 4 to 10 zones.

Effluent is demand-dosed from the pump chamber into the field, typically in 150–250 gallon doses once or twice per day.

The flow of effluent into each section is controlled by a 2-inch ball valve connected to a manifold with the remaining field valves. These valves and manifolds are housed inside one or more large green sprinkler-control boxes or a wooden box constructed by the installer.

The valve box is generally located at the head of the field on the upslope corner, opposite the observation ports, which appear as a series of white pipes spaced approximately 8–12 feet apart.

Valve Identification and Field Layout

During installation, each field section valve should be permanently noted on the as built or septic drawing with:

• Section number
• Compass direction
• Upslope or downslope designation

The #1 valve controls the uphill section closest to the valve box. The highest numbered valve controls the lowest downslope section farthest from the valve box.

For example, if the field is located to the left and downslope from the valve box:

• The #1 valve on the left controls the upper section.
• The #6 valve on the far right controls the lowest section of the field.

Rotating Field Sections

These systems are intentionally designed with one extra section so that one section can rest while the others remain in operation.

For example:

• In a 5-section system, 4 sections operate while 1 section remains off.
• The resting section should remain off for approximately 6 months to allow the soil to dry and recover.
• After 6 months, that section is turned back on and the next section is turned off.

This rotation process should continue in sequence indefinitely.

Properly rotating sections helps extend the life of the soil treatment area and improves the long-term performance of the septic system.