Skip to main content

Thurston County, Washington

The content on the Thurston County website is currently provided in English. We are providing the “Translation” for approximately 10 languages. The goal of the translation is to provide visitors with limited English proficiency to access information on the website in other languages. The translations do not translate all types of documents, and it may not give you an exact translation all the time. The translations are made through an automated process, which may not result in accurate or precise translations, particularly of technical and legal terminology.

Community Planning and Economic Development

County permit and application forms ask many detailed questions about a property's sources of drinking water and your plan for treating sewage. Whether you're installing a new well and septic system, or providing information about what's already on site, be prepared to do some research, and/or hire professional septic designers or engineers to do property inspections, reports and drawings. Each property and project is unique. The county's Environmental Health (EH) division manages septics and wells, please consult with experts, or contact EH at 360-867-2673 if you don't find the info you need below.

Raw / Undeveloped Land Requiring a First-Time Septic System Installation: You Need a Well & Permits


Raw / Undeveloped Land Requiring a First-Time Septic System Installation: You Need a Well & Permits

You'll need a septic system permit completed by a licensed septic system designer or Professional Engineer if you build a new home, or if you build on an undeveloped property that isn't or won't be connected to a city sewer system. These permits come before you apply for other permits.

  • Gather information & Hire a Septic Expert
    • Find forms on the Environmental Health division's Septic System web page scroll down to the section titled Applications for New On-site Septic Systems and Repairs for those forms.
    • Hire a septic designer (see county design pros list) or Professional Engineer to complete the test hole work, site plan drawings showing where the septic system and well will be located, and answer the detailed questions on the forms. If applying for an additional residence or Accessory Dwelling Unit, the professional you hire should also evaluate the property to ensure it is able to accommodate these uses. The type of soil, size of property, and drinking water source will determine what your property can accommodate.
  • After you submit your application
    • County staff review your submitted application packet & come onsite to evaluate the soils and the property.
    • County may issue a Conditional Site Approval letter with list of conditions and next steps for you to take.
    • Complete the CSA conditions, purchase your permit and have the system installed.
    • Have your designer submit a drawing of the installed system called a Record Drawing to the county. Once accepted a stamped copy of the Record Drawing will be provided to the applicant.
    • After county approves the Record Drawing, you'll get an Operational Certificate. Depending on the type of system and where it is installed in the county you may need to renew your Operational Certificate on a routine basis. 


Properties that Already have Septic Systems: May or May Not Need Permits (but you will need lots of information)

You may not need a septic permit If adding a structure or manufactured building on a property that already has a septic system or is connected to city water and sewer. You may need permits if the existing septic system isn't sized properly for the proposed use. Including a difference in the number of bedrooms the system is sized to accommodate or is no longer functioning or in need of certain repairs. 

Even if you don't need permits, the septic and well forms you fill out will include many detailed questions about the condition, size and configuration of the existing septic system. Be prepared to do research using look up links below or hire experts to assist you through this process.

You also need an inspection of the septic system, and if necessary, a pumping, by a licensed septic system professional within the previous three years prior to submitting your application. Additionally, you will also need to submit a detailed site plan showing all septic system components, wells, water lines, sewage transport lines and structures on the property. Septic system components include the septic tank, any pump chambers, the entire drainfield, and reserve drainfield area.



For new and repair installations of septic systems inspections are arranged by your septic installer after installation.  Installers call Environmental Health to schedule final inspections. Inspections of existing systems are needed prior to time of transfer (Sale of a property that has a septic system) reports and building applications are conducted by certified professionals such as septic system pumpers and submitted to an online database available to the county.


Other Important Septic Forms & Inspection Information