Sand Filter System

After the septic tank, a pump sends pressurized effluent to a large underground box which is full of sand and drainrock. Effluent is spread evenly over the surface of the sand via a pressurized pipe network (similar to a pressure distribution system). The dirty effluent filters through the sand and collects in a sump at the bottom. A second pump sends the relatively clean effluent to the drainfield where the final treatment occurs and the effluent is disposed in the soil.

Since wastewater leaves a sand filter system as high-quality effluent, the soil in the trench or mound soil treatment system may be better able to accept it, and the system should last longer. Because sand filters produce cleaner wastewater, they are useful for sites that have been compacted, cut, or filled; and for environmentally sensitive areas like those near lakes, in shallow bedrock areas, aquifer recharge areas, and wellhead protection areas. Pretreatment may allow a reduction in the three-foot separation required between the soil treatment system and the limiting soil layer. Researchers in several states are testing reduced separation distances in soil treatment systems receiving wastewater pretreated in a sand filter

Services We Provide

Service Area

  • Battle Ground, WA
  • Brush Prairie, WA
  • Camas, WA
  • Hazel Dell, WA
  • Hockinson, WA
  • La Center, WA
  • Meadow Glade, WA
  • Mill Plain, WA
  • Ridgefield, WA
  • Vancouver, WA
  • Washougal, WA
  • Woodland, WA
  • Yacolt, WA