Compare conventional drain fields, mound systems, sand filters, and aerobic treatment—and learn why soil testing comes first.
Start with the site evaluation
A qualified professional and local health authority may require soil observations, a percolation test, test pits, survey information, and a proposed home location. Heavy clay, fast-draining sand, shallow rock, steep slope, or high groundwater can change the design.
Conventional tank and drain field
A conventional system settles solids in a tank and distributes effluent into suitable soil. It is often the simplest option when the lot has adequate usable area, separation distances, soil, and elevation.
- Conventional gravity system
- Mound or sand-filter system
- Aerobic treatment unit
- Required reserve or replacement area
Alternative systems for constrained sites
Mound systems raise the treatment area; sand filters add treatment; aerobic treatment units use mechanical aeration. These options may address difficult conditions but can add design, power, monitoring, maintenance, and replacement costs.
Protect the reserve area and budget
Many jurisdictions require space for a replacement field. Keep structures, driveways, wells, and heavy equipment clear of the approved areas. Price engineering, permits, installation, inspections, pumping, electricity, service contracts, and future repair.