Low Pressure Dosing System (LPD)

Low-pressure dose systems, or LPDs, offer an alternative where soil and topographical conditions do not permit the placement of a conventional septic system. This is especially true where the topography requires the drain field to be located uphill from the septic tanks or where there is uneven terrain that would not be conducive to the placement of a conventional gravity system. LPDs use an additional tank called a pumping chamber as well as the septic tank and the drain field. An LPD consists of small perforated pipes in shallow, gravel lined trenches where wastewater is pumped into the drain field to where the entire field is saturated. The field is then left to drain and filter and clean the wastewater. This promotes good bio-processing by bacteria and other micro-organisms. Advantages include a reduction in the amount of land area required by the drain field compared to a conventional system and the uniform use of the entire drain field. Disadvantages include a potential for infiltration by roots, clogging of drain holes by solids that escape the pumping chamber, and a potential for wastewater accumulation in the drain field. These systems require a maintenance contract and regular inspections