Application for secondary dwelling or Accessory Dwelling Unit (ADU)

When submitting to obtain Septic/Onsite Wastewater Treatment System (OWTS) approval from DEH for your proposed secondary dwelling or accessory dwelling unit (ADU) connecting to a proposed new Septic or OWTS, please visit the New Development or Individual Feasibility Testing webpage.

When submitting to obtain Septic/Onsite Wastewater Treatment System (OWTS) approval from DEH for your proposed secondary dwelling/accessory dwelling unit (ADU) connecting to an existing Septic/OWTS, please provide the following to [email protected]:

1. A completed Plan Review Application
2. One (1) copy of site plans to scale (1” = 20’). Plans must include:
   1. Proposed Septic/OWTS upgrades as required
   2. Location of existing septic tank and leachfield (As-built) 
   3. Scope of proposed building project
   4. Minimum setbacks as required on page 3.11 and 3.12 of the Onsite Systems Manual
   5. Approved water supply (well/public water)
   6. Any additional requirements, as detailed in the Onsite Systems Manual
3. One (1) copy of proposed floor plans

Additional soil testing may be required to determine minimum sizing and setbacks of Septic/OWTS by completion of one or more of the following:

1. Site assessment
2. Soil analysis
3. Percolation testing (completed by REHS, Professional Civil Engineer, or Professional Geologist)
4. Current (within last 3 years) Septic Pumper’s Report including 30-minute water test if existing Septic/OWTS is to be utilized

For additional feasibility testing please visit the New Development or Additional Feasibility Testing webpage.

Once all requirements have been completed and plans are ready for an approval stamp, digital copies will be stamped and provided to the Project Contact Person electronically. For paper plans, additional copies will need to be submitted to DEH for stamping.

The DEH reviewed and approved plans will need to provide to the applicable jurisdiction’s Planning/Building Department for inclusion in the building packet. The Septic/OWTS Permit will be issued with the issuance of the building permit prior to the start of Septic/OWTS construction.

For City/Towns not under the jurisdiction of the County Planning/Building Department, request for a Septic/OWTS Construction Permit will need to be submitted to DEH along with a Construction Permit Application.

Note: An onsite inspection may be scheduled for verification of minimum requirements. Additional fees and requirements may apply. All applicable fees must be paid in full prior to any services provided by DEH (inspections, plan reviews, approvals, etc.). Projects/Submittals are reviewed in the order received - with the exception of septic system failures.  Please refer to the current DEH Fee Schedule for more information.

DEH will not begin any work until all the items noted above and payment are received.

Please forward all large/over-sized sitemaps and necessary documents to the following:

County of Santa Clara – DEH
RE: (Project number, once assigned)
1555 Berger Drive #300
San Jose, CA  95115