Septic
Sonoma County has over 40,000 septic systems serving 100,000+ residents. About 70% of these were built before more stringent standards were enacted in 1975, so there are a number of septic systems in the County that would not be allowed to be built today. Currently, a large number of nonstandard systems, which include engineered and experimental systems, are in use. As the State of California is moving toward uniform statewide septic standards which could limit these nonstandard systems, knowing your septic is a must.

Sonoma County is complex geologically and this contributes to the challenges in septic system construction; we have over 55 major soil types. The three issues to address when planning a septic system are:
Shallow soils not enough soil to absorb the effluent (about 3 feet is needed)
Low permeability the soil is not porous enough to absorb the effluent
High groundwater in the rainy season the ground water could be contaminated

Percing the property is the process to determine whether a septic system can be used and, if so, how large a house (measured in number of bedrooms) maybe built on the property. The process usually includes a pre-perc to obtain soil samples, a perk test to determine absorbency and sometimes a wet weather groundwater test.

If the site checks out, a septic plan is submitted for approval and, if approved, a permit is issued. Depending on the property, a standard septic system or a non-standard septic design will be specified. A standard system is best. Some types of nonstandard systems can cost $30,000+, require more maintenance and may require annual permitting.