I'm submitting a building permit application. What will the septic review process look like?

Alternate Description of Flow Chart

1. Get Started: This is where you begin the process of determining what the septic review process will be for your building permit application.
2. Building Permit Application: Once you submit your building permit application, your application may or may not require septic review. Septic review is required for building permits that require a set of plans. Septic review is not required for the following:
• Furnaces
• Water Heaters
• Re-Roofs
• Siding
• HVAC
• Electric Service
• Electrical Repairs
• Interior Wall Coverings
• Dry Rot Repair (less than 40 linear feet)
• Deck Repairs
3. Existing Septic: For building permit submissions for projects that require a set of plans, Permit Sonoma staff check to see whether or not there is an existing septic system on the property. If there is no septic system, and the property is not hooked up to sewer, you will be required to get a new septic system before proceeding with the proposed building project. You can find instructions on permitting for a new septic system on the new permit flowchart.
4. Cesspool: Once the existing septic system has been verified, Permit Sonoma staff then check to see if the existing septic system is a cesspool. Cesspools are not allowed authorized in Sonoma County. Therefore, if you have a cesspool, you will be required to get a new septic system before proceeding with the proposed building project. You can find instructions on permitting for a new septic system on the new permit flowchart.
5. Flow Increase: After staff have confirmed that there is an existing septic system and it’s not a cesspool, they then check to see if the proposed project will result in an increase in wastewater flow. For example, will there be any additional bedrooms? Or will there be new or additional process flows? If there is an increase in flow, a Qualified Consultant will need to evaluate the existing septic system to see if it has the capacity and functionality for this additional flow. If there is a flow increase and the existing septic system does not have the capacity and/or functionality for the flow increase, then you will have to replace your septic system. You can find instructions on permitting for a new septic system on the new/replacement permit flowchart.
6. Square Foot Increase: The next thing staff check for is whether the project proposes and increase in square footage of existing structures or a new structure. If not, the septic review of the permit application is complete. However, if there is an increase in square footage, staff then check to see if there is a land constraint created by this increase in square footage. Staff look to see if the proposed increase would encumber the parcel to the point the replacement reserve septic area needs to be property established. Examples of land encumbrance include paved or covered structures and setbacks from wells, septic systems, creeks, steep or cut slopes. If there is a land constraint, you will be required to have a septic reserve area. Your septic area will also be evaluated. If the septic area is adequate, the septic review will be complete.

Building Permit Types

Septic review required for building permits that require a set of plans.

These do not include:

• Furnaces
• Water Heaters
• Re-Roofs
• Siding
• HVAC
• Electric Service
• Electrical Repairs
• Interior Wall Coverings
• Dry Rot Repair (less than 40 linear feet)
• Deck Repairs

Existing Septic

Is there an existing septic system on the property?

Cesspool

Is the existing septic system a cesspool?

Flow Increase

Is there a proposed increase in wastewater flow?

• Bedroom Count
• New/Additional process flow

Evaluate Existing Septic

Qualified Consultant evaluates for capacity and functionality.

Square Foot Increase

Is there a proposed increase in square footage of existing structures or a new structure?

Land Constraint

Does the proposal encumber the parcel to the point the replacement reserve septic area needs to be properly established?

Land Encumbrance

• Paved or covered with structure(s)
• Setbacks from wells, septic systems, creeks, steep or cut slopes.