Alternative Septic Systems Approved and Installed in Sonoma County

Alternative Onsite Wastewater Treatment Systems (OWTS) are approved non-standard OWTS that have demonstrated in the non-standard Experimental phase to function reliably in a variety of conditions and which are protective of water quality and environmental health. Sonoma County has approved and installed numerous types of alternative OWTS. This page lists the types of alternative systems that are approved and installed in the County.

Wisconsin Mound System

An above ground system built with a gravel bed and sand area.
Pressure distribution
Sites with shallow soils

At Grade System

An above ground system built with gravel
Pressure distribution
Sites with shallow soils

Drip System

Shallow subsurface dispersal
Time dosing, pressure distribution and flexible tubing
Sites with shallow soils

Shallow Trench Pressure Distribution (STPD)

Pressurized trench system for sites with shallow top soils over slowly permeable or fractured rock.
On slopes up to 30%

Shallow in Ground (SIG)

Utilize shallow depth trenches and pressure distribution
Minimum of 24 inches of soil below the trench bottom

Advanced Pre/Treatment Units Approved and Installed in Sonoma County

Peat Moss Systems
Recirculating Sand Filter
Single Pass Sand Filter
Advantex Units (filter fabric)
Clearstream
Bio-Microbics Fast
Hoot Aerobic
Microseptic Enviroserver
Multiflo
Norweco Singulair
Norweco Biokinetic Singulair
Nayadic
Peat filter
Southern Aerobic
Whitewater Aerobic

Experimental Systems Approved for Installation in Sonoma County

Bottomless Sand Filters
Gravel-less Pressurized Dispersal Channel (GPDC)

Experimental Systems Under Review in Sonoma County

Eljen technology is currently under review as a pretreatment and dispersal system.

Advanced Pre/Treatment Units Approved Under the Experimental Program

Aqua Filter
Pura System SBR (aeration system) Models PS1-4 through PS1-8; PS1-9 through PS1-14
EZ-treat (Recirculating Synthetic filter)
Aqua Klear (Air diffuser)