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Sonoma County Gazette
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Sonoma County Septic (OWTS) Permitting Changes Now in Effect

Aug 17, 2019


As of August 15, 2019, the Sonoma County Onsite Wastewater Treatment System (OWTS) Manual version 7.0 is in effect.  Customers are hereby advised that any septic applications will be required to comply with the provisions of the OWTS Manual version 7.0.  Customers are further advised of the following updates to Permit Sonoma’s permitting procedures:

  1. Applicants for septic permits will be required to visit with a Permit Technician to submit septic applications.  Permit Sonoma will no longer accept drop off septic applications.  This change is being implemented to provide better customer service to our septic applicants and to facilitate consistent business practices regarding permitting of construction work.
  2. Permit Sonoma has consolidated and simplified the types of septic permit applications customers may submit.  Applications for New OWTS, Replacement OWTS, and Repair OWTS will be accepted in compliance with the newly adopted OWTS Manual.  Applications previously allowed under the retired OWTS Manual version 3.0 (including but not limited to Code Compliant OWTS, Class I OWTS, Class II OWTS, Class III, Abatement Repairs, Voluntary Repairs, Addition Repairs, etc.) will no longer be accepted.
  3. Building permit applications will be reviewed for septic approval in compliance with the newly adopted OWTS Manual.  However, Permit Sonoma must also review building permit applications in compliance with the California Plumbing Code, Appendix H, Sections H 101.6 (which requires no structure be erected on a lot where the structure impairs the usefulness of the 100 percent expansion area) and Section H 101.7 (which requires that a site cannot be developed beyond its capacity to properly absorb sewage effluent).  Therefore, adequate reserve replacement area will be required to be clearly shown and identified on building site plans for building permits that require plan check.

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Onsite Waste Treatment Systems (OWTS) Manual

The Onsite Waste Treatment Systems (OWTS) Manual provides the regulations, procedural and technical details governing individual onsite wastewater treatment systems (also referred to as septic systems). State law mandates the State Water Resources Control Board (State Water Board) adopt standards for regulation of onsite waste treatment systems ( State Water Board OWTS Policy).

The OWTS Manual complies with the State Water Resources Control Board OWTS Policy Tier 2 Local Area Management Program (LAMP) requirements. OWTS Manual The OWTS Manual (link)  and associated documents (Links) are presented below.

Entire Manual in a Single Document OWTS Portfolio (PDF: 8.99 MB)

Manual Broken Into Sections / Accessible Version: Each document below is in PDF format and is under 550 kB unless otherwise noted. California Plumbing Code Memorandum OWTS Cover and Table of Contents

Section 1 – General Section 2 – Sewer Connection Required

Section 3 – Acronyms and Definitions Section 4 – Criteria for All OWTS

Section 5 – Abatements, Abandonments and Repairs of Failing Systems

Section 6 – Requirements for Approval of Building Permits

Section 7 – Site Evaluation Methods and Investigation Requirements 

Section 8 – Criteria for OWTS Components

Section 9 – Criteria for Standard OWTS

Section 10 – Criteria for Water Reuse

Section 11 – Criteria for Commercial, Industrial, and Institutional OWTS

Section 12 – Non-Standard Experimental and Alternative OWTS Approval Process

Section 13 – Non-Standard Experimental and Alternative OWTS Standards (Size: 2.61 MB)

Section 14 – Non-Standard and/or Commercial OWTS Operational Permit and Monitoring

Section 15 – Vesting Certificates

Section 16 – Subdivisions and Lot Line Adjustment Requirements

Section 17 – Variance Requirements

Section 18 – Variance Prohibition and Special Standards Areas (Size: 3.40 MB)

Section 19 – Dispute Resolution

Section 20 – Tier 3 Treatment, Monitoring, Inspection and Sampling for Supplement Treatment Units

Section 21 – Waterless Toilets Appendix A – Experimental and Alternative OWTS


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