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SAN-004 Outside Service Area Sewer

Revised 01/22/2015

Summary of the background information and the necessary requirements to request public sewer service for a property located outside of the service area of a County sanitation district or zone.


Outside service area sewer can be obtained either by annexation to a sanitation district or zone or through an Outside Service Area Agreement (OSAA, or “sewer agreement”) with a sanitation district or zone. The County will determine which method to use, depending upon the location of the property. A request for outside service area sewer service must be approved by the Board of Directors of a sanitation district or zone; the Permit Sonoma does not approve the sewer service request.

Annexation is used when property is located inside the urban service area of a sanitation district or zone. Property annexed to a sanitation district or zone may be developed to the full extent allowed by zoning regulations, including construction of new buildings that require sewer service.

When property is located outside of the urban service area of a sanitation district or zone, sewer is provided by a sewer agreement. Sewer agreements are typically written only for existing buildings Once connected to sewer, a building may be repaired, remodeled or replaced. Residential additions and new buildings that are not connected to sewer are also allowed. However, additional residential units (including second dwelling units) cannot be constructed and non-residential uses cannot be expanded.

Vacant property within the southern portion of the Sonoma Valley County Sanitation District Sphere of Influence may be connected to public sewer and developed for new residential use, depending on zoning, so long as the development does not exceed 1.0 Equivalent Single-family Dwelling (ESD) sewer connection assessments. Please consult with the Sanitation staff at Permit Sonoma for information regarding the location of your property and the availability of sewer service.

If a request for sewer service for a property with a septic system results in a sewer agreement, the applicant must demonstrate that the property has a failed septic system. The applicant is required to obtain a statement from a private Registered Environmental Health Specialist (REHS) or a Registered Civil Engineer (RCE), describing the condition of the existing system. The applicant is also required to apply with the Permit Sonoma Well & Septic Division for an inspection of the septic system.


After a completed SAN-005 Application for Outside Area Sewer (PDF: 363 kB) has been submitted, Permit Sonoma Sanitation staff will prepare and distribute a referral describing the project, to various County agencies for review and comments. An environmental review in accordance with the California Environmental Quality Act (CEQA) is required unless the requested sewer service is specifically exempt from CEQA requirements. Additional information or studies may be required to complete processing of the application.

When all agencies have responded, Permit Sonoma Sanitation staff will prepare the necessary documents for outside service area sewer. When these documents have been reviewed and approved by Permit Sonoma and the sanitation district or zone, Permit Sonoma Sanitation staff will forward the documents to the sanitation district or zone’s Board of Directors for approval of the requested service.

Following approval of the requested sewer service by the sanitation district or zone’s Board of Directors, the applicant must submit an application for Annexation directly to the Local Agency Formation Commission (LAFCO) which has final authority for such proposals. For an OSAA, pursuant to state law, Permit Sonoma (or other governing agency) will submit the application to LAFCO on the applicant’s behalf. The LAFCO application and fee schedule can be found by accessing the LAFCO website at: Upon LAFCO approval of an annexation proposal or OSAA application and recordation of documents with the County Recorder’s Office, the applicant may apply for permits to construct sewer piping to serve the property. All sewer construction permits must be obtained from the Sanitation Section of Permit Sonoma.

If an applicant is required to extend a public sewer main to serve the property, improvement plans of the sewer design must be prepared by a registered civil engineer, plan checked by the Permit Sonoma Sanitation Section and approved by the sanitation district or zone before a permit can be issued to construct the sewer main.

Required Application Materials

A complete application must have all of the following:

  1. Application. Both must be submitted:
  2. Site Plan. Provide a site plan including the information required on the Minimum Standard Site Plan requirements CSS-019. The site plan must show property lines, roads, highways, creeks and streams near the property, the locations of buildings, the septic tank and leach field, and any wells including those on neighboring properties within 100 feet of the subject property.
  3. Deed of Ownership. Provide a copy of the deed of ownership of the property.
  4. Application Fee. See the current Permit Sonoma Public Sewer & Water Systems fee schedule or visit the Engineering cubicle at Permit Sonoma.

Time Line

The process, from submittal of the application to the Permit Sonoma Sanitation staff, to approval by LAFCO and recording of the documents will take approximately six months but may take longer depending upon various factors affecting the process. These factors include, but are not limited to, work performed by a civil engineer, meetings and site visits by County staff and others, preparation of documents, review and approval of documents, and Board of Directors’ meeting schedule.

Additional Permits and Fees

Additional permits and fees that may be required after the outside service area sewer request has been approved include, but are not limited to, a Septic Tank Destruction Permit for the existing septic tank, an Encroachment Permit to excavate in a County road, a Sewer Plan Check Permit for review and approval of the proposed sewer piping, a Sewer Construction Permit for inspection of proposed sewer piping, and a Sewer Connection Permit for payment of connection and use fees.

The applicant is advised to obtain an estimate of the required fees prior to submitting an application for outside service area sewer service. For assistance in estimating the fees, please visit the Engineering cubicle at Permit Sonoma.

Contact Information

Contact Us by Phone
2550 Ventura Avenue
Santa Rosa, CA 95403
38.465074, -122.723705

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Sanitation Codes and Standards
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