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

• 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

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

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

• 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)