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Well and Septic Systems

The Well and Septic Division staff reviews all development proposals that will rely on water wells or septic systems. They also review permit applications for septic system repair or upgrade. Their focus is on protecting health by ensuring that water wells are properly constructed and septic systems protect surface and groundwater quality. Sonoma County's soils are notoriously poor for septic systems, so this is a sometimes challenging mission.

Sanitation Sewer Information
A sanitary sewer system collects and transports waste from indoor plumbing fixtures to treatment plants.

Contact Information:

End of Extended COVID Permit Expiration Date

In order to support the difficulties the COVID-19 pandemic brought to the community, Permit Sonoma offered customers a two-year extension above and beyond the regular timelines for various ministerial applications and permits. The conditions attributing to the local emergency no longer exist and the Board of Supervisors is rescinding the local emergency as of May 16, 2023. As such, the policy extending the expiration dates will sunset effective May 17, 2023.

This change does not affect permits that have already been extended. All applications received beginning May 17, 2023 will be valid for one year, and the COVID-19 extension will not be applied.

View Affected Permit Types


  • Inspections
    Inspections are necessary to determine whether well or septic construction work is compliant with code requirements, and that the scope of work is in accordance with the related permits.
  • Inspection Scheduling
    Schedule and find out the results of your inspections in one of 3 ways.
  • Well & Septic Inspection Codes
    Find the 3 digit codes needed to schedule inspections.

Sonoma County Code

Operational Permit (OPR) and Monitoring for Non-Standard Septic Systems

The purpose of the Non-Standard Septic System Operational Permit and Monitoring (OPR) program is to monitor non-standard septic systems to ensure they are operating properly for the protection of public health and groundwater resources.

Permit Sonoma administers the county’s OPR program. The property owner’s role in the OPR program is to properly maintain and operate their septic system.  Part of that responsibility is to submit biannual monitoring information to Permit Sonoma.

Seasonal Testing

  • Wet Weather Percolation and Groundwater Testing
    Septic Systems: To protect groundwater from pollutants from septic systems, the Onsite Wastewater Treatment Systems (OWTS) Manual requires that wet weather groundwater table determinations be conducted under specific conditions.
  • Dry Weather Well Testing
    Water Wells: Sonoma County Code requires dry weather well testing for issuance of building permits for new dwellings located in marginal or scarce water zones.

Graywater Systems

Graywater is wastewater collected from showers, bathtubs, bathroom sinks, and clothes washing machines. Graywater does not include water from toilets, kitchen sinks, or dishwashers. Graywater can be routed to your landscape to help meet your irrigation needs.