A building permit is required when you want to make significant changes by adding additional square footage (bedrooms, deck, recreation room, detached garage, etc.) to your property. Public Health – Seattle & King County is required to review remodel projects when the house is served by a septic system*. Construction should not begin until the local building department authorizes the project. Your septic system condition and capacity must be comparable to the changes made to the house after the remodel is complete.

*A septic system is also referred to as an “on-site sewage system” in official documents, forms and applications.

Step-by-Step Process:

1.	You may apply for this review prior to or at the same time as the Building Department’s review of your application.
2.	While preparing your application, it is important to accurately describe the location of all septic system components on your site plan. Click here for information about how to request a drawing or "as-built" of your septic system.
3.	The application must be filled out completely with 3 copies of everything.
4.	Each application is reviewed by an inspector and receives a site visit. Examples the inspector are looking for includes: a. Age of septic system b. Condition of system c. Type of system d. Location of system as compared to area of remodel e. Presence of a reserve drainfield area f. Size of remodel existing square footage vs. square footage being added g. Use of addition are bedrooms being added? number of bedrooms equals occupancy equals size of septic system h. Water source a drinking water well requires certain setbacks to structures structures must be served by an approved water source i. As-built and past permit history
5.	Due to the scope of your remodel and condition, location and age of your septic system, you may be required to have the septic system evaluated by a licensed septic professional. The inspector will notify you in writing what this evaluation must include and what type of septic professional must be contacted.
6.	You may also be required to upgrade or replace your septic system. For example, a house with an older septic system and a proposal to tear the house down to the foundation and rebuild it would require a new septic system. Click here for more information about upgrading or replacing your septic system.

If you would like to appeal Public Health's decision/order, click here for more information.

Forms used by your septic system professional:

• Application for Public Health – Seattle & King County Approval of Building Permit (submit 3 copies)

Fees:

• Wastewater Program Fee Schedule