Well & Septic Frequently Asked Questions

Generally, dry weather well testing may be performed during the following dates: Springs and shallow water wells (less than 50 feet deep): July 15 to October 1 of each year

Deep water wells (greater than 50 feet deep): July 15 to October 1 of each year (or as extended by Permit Sonoma Director)

Find out more information about dry weather well testing and testing dates, including any extensions in testing dates: Dry Weather Well Testing

The County is divided into districts which are shown on our Well & Septic Environmental Health Districts map (PDF). This map also lists which staff members are assigned to each district. Once you determine the staff name for your area, you can find their contact information on the Permit Sonoma Employee Directory.

If you do not receive a form by mid-March (for end of March deadline) or mid-October (for end of October deadline), contact Well & Septic staff at (707) 565-2658 or email at PermitSonoma-OPR@sonoma-county.org. End of March and end of October deadlines still apply.

Detailed instructions for filling out self-monitoring forms: WLS-014 How to Monitor an Onsite Wastewater Treatment System (OWTS)

More Information: Non-Standard Septic Systems Operational Permit (OPR) and Monitoring

Files are retained in the Records area at Permit Sonoma and can be accessed during regular Permit Sonoma Public Lobby hours. All files are arranged by street address. We have septic records from the early 1960's to the present and well records from the early 1970's to the present. In some rare instances we have records from earlier dates. Well logs are deemed confidential by State Law and can only be viewed by the property owner or a consultant working on a contamination clean-up plan.

The following permits require a Well and Septic Clearance:

• All building permits that require a plan check
• Any repair or remodel to a structure that is over $10,000 in permit valuation
• Any building permit that may impact the septic system
• Grading permits
• Pool/Spa permits

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The Public Health Division of the Health Services Department provides water testing services in their testing lab, located at 3313 Chanate Road, Santa Rosa. Testing is done for a fee and you must use the sterilized bottle they provide. They will also furnish instructions for taking water samples. This lab tests for enteric bacteria, namely coliforms and fecal coliforms in water. View a list of other state approved private labs for testing your water.

• Find out more information about Well Water Quality from the Environmental Health & Safety Division of the Health Services Department.

You must submit 2 floor plans for proposed structures and 2 sets of sites plans showing the location of the septic system, well and all other structures. This would include houses, outbuildings, driveways, pools, decks, etc. If the clearance is for an existing structure, your plans must show the existing floor plan and what changes/additions will be done.

Pre-Percolation is an on-site evaluation with a Permit Sonoma Environmental Health Specialist and a septic consultant. The purpose is to determine site suitability for a septic system. A backhoe or excavator with an operator must be present at the time of the pre-perc. The type of Percolation Test required will be determined at this time.

A Percolation Test determines the soil's capability to absorb liquid over a specific period of time. This allows a determination to be made regarding the size and type of septic system that will be required. The test must be certified by a Registered Civil Engineer or a Registered Environmental Health Specialist. Consultants who provide these services can be located in the telephone book's yellow pages under the heading "Septic Tanks and Systems Consultants".

A Wet Weather Percolation Test is required on sites with expansive clay soils. This test is conducted during a specific time frame in the wet-weather season. The time frame begins after rainfall has reached a minimum of 50% of annual average. This occurs during the first quarter of each calendar year if there is sufficient rainfall.

You may also be required to perform a wet-weather ground water level determination. This is a measurement of the depth to ground water on your lot that is made in a 10 day window following a heavy rainfall during the wet weather testing period.

Find out more information about wet weather percolation and groundwater testing and testing dates, including any extensions in testing dates: Wet Weather Percolation and Groundwater Testing

Vesting is a means of guarding against changes in septic regulations before you build. An approved septic design can be vested for 3 years. An installed approved septic system can be vested for 2 years. A Vesting Certificate transfers with the property if it is sold. A septic plan check must be performed to receive a vesting certificate. 2 sets of plans must be submitted. One set will be retained by Permit Sonoma and the other set will be returned to the applicant stamped "Vested" at time of approval. Fees will be charged per the current fee schedule.

No. Vesting Certificates are issued in compliance with Sonoma County Code, Chapter 24, Article V which states that the issuance of a vesting certificate is solely a right to construct a septic system with the intent to protect the certificate holder from subsequent changes in the law thereby providing some degree of certainty for a limited period of time. There is no provision to allow a vesting certificate to be renewed.

However, an applicant may submit the original septic system design approved under an existing vesting certificate to be reviewed for compliance with the standards in effect at the time the new septic system design application is submitted. Once the new septic system design application is approved then a new vesting certificate may be requested.

Separate fees will apply for the reviews associated with the new septic system design application and new vesting certificate application.

1. Find Your Zoning to verify that an Accessory Dwelling Unit is allowed on the property by the Zoning Code. You may be required to obtain a Zoning Permit. Contact the Planning Division to confirm if your property's eligibility and to check permitting requirements or if you have any Zoning questions.
2. When this has been done, you will need an upgrade of your current septic system or a new septic system. You should retain a septic consultant to assist you with this process. Consultants who provide these services can be located by searching for "Septic Tanks and Systems Consultants."
3. In addition, if you are in a water scarce area as defined in the Sonoma County General Plan, you will need to do dry weather well yield testing.

A Permit Sonoma Environmental Health Specialist can evaluate your septic system after your septic tank has been pumped. The Environmental Health Specialist can provide you with more information regarding your septic system if they are present when the pumping takes place. If requested they will also inspect the on-site water system and test for bacteriological quality. There is a fee for this service defined in the current fee schedule.