What is a sand filter septic system?

A sand filter septic system adds a treatment step between the septic tank and the drainfield, the soil area that receives the tank’s liquid. Effluent, the liquid leaving the tank, is pumped in doses into a box, typically PVC-lined or concrete, filled with a specific sand, treated as it filters through, and then sent to a drainfield.

Where are sand filters used?

Sand filters are one of the alternative systems that can be used where soil or site conditions are not well suited to a standard drainfield.¹ Another alternative is the mound system. Ask the agency that issues septic permits where the lot is how much soil the drainfield after a sand filter needs above the water table.

What does a sand filter add?

Sand filters generally cost more than a conventional septic system.² A sand filter uses a pump and normally needs regular checks.³

Citations

1. Washington State Department of Health, Understanding and Caring for Your Sand Filter System (DOH 337-089); Virginia Cooperative Extension, On-Site Sewage Treatment Alternatives (448-407). ↩

2. U.S. EPA, Types of Septic Systems; Virginia Cooperative Extension, On-Site Sewage Treatment Alternatives (448-407). ↩

3. Virginia Cooperative Extension, On-Site Sewage Treatment Alternatives (448-407); Washington State Department of Health, Understanding and Caring for Your Sand Filter System (DOH 337-089). ↩