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On-site Wastewater Treatment System

Last modified: 7/22/2014 11:15 AM

The Department of Environmental Health (DEH) and the Planning Office are collaborating to update regulations for On-Site Wastewater Treatment Systems (OWTS), also known as septic systems. The update would primarily affect owners of properties within the unincorporated part of the County who have failing septic systems or who are interested in new development, such as new single family homes, secondary dwelling units, or major home additions. Owners of existing homes with functioning septic systems would not be affected. The update would make possible the use of so-called “alternative” septic system technologies, which can pre-treat wastewater before it is discharged to underground drainfields and also incorporate more flexible and efficient drainfield designs. These alternative technologies help protect the environment and provide design options for property owners whose lots are constrained by limited space, high groundwater conditions, or steep slopes.

Key Documents


Department of
Environmental Health
Draft OWTS



The proposed regulatory update would include revisions to the Department of Environmental Health’s On-Site Wastewater Treatment Ordinance, the Health and Safety Chapter of the County’s General Plan, and the Planning Office’s Zoning Ordinance. Besides allowing for alternative septic systems, the On-Site Wastewater Treatment Ordinance would eliminate the 1 acre minimum lot size requirement for private sewage disposal system installation in the Lexington Basin area of the Santa Cruz Mountains. The General Plan revision would update policies and supporting descriptive text that reference and enable the use of alternative OWTS. The Zoning Ordinance would be revised to eliminate the 5-acre minimum lot size requirement for establishing new secondary dwelling units in the San Martin Planning Area.


For Additional Information, please contact:

Department of Environmental Health
Heather Forshey
(408) 918-1958
Ann Peden
(408) 918-3480

Planning Office
David Rader
(408) 299-5779