Frequently Asked Questions

A septic system, also known as an on-site sewage system (OSS), stores, treats, and disposes of the things you flush and send down drains. There are many different types of systems. Some are simple, using only a tank and a drainfield, and others are more complex, requiring pumps, filters, or specially designed materials. The term on-site sewage system is used in the state and county code, on permit application forms, and by industry professionals to refer to different types of septic systems.

The Snohomish County Health Department offers an online database of septic system records for properties in Snohomish County, which can show you what your existing system looks like and what type it is. To find out if you have a septic system, you can enter your Property Tax Account number or address into the OnlineRME database.

Please refer to our page with septic system sizing information on the guidelines that are used by professionals. 

State law (Chapter 246-272A-0270) requires that homeowners inspect and maintain their septic systems to ensure it is functioning properly. Please see our septic maintenance and repair webpage for detailed information on how to care for your system, including do's and don'ts, landscaping tips, signs of failure, safety, and more.

Inspections: For a gravity system, it should be inspected every 3 years. For an alternative system, it should be inspected annually, unless otherwise specified by the manufacturer. For details, see our monitoring & maintenance frequency cheat sheet.

Pumping: How often your system will need to be pumped depends on many factors, such as the number of people in your household and how well you treat your septic system. For some households, the tank may need to be pumped every two years, and for others it may be five or more years before it needs to be pumped. Because it can vary, it is recommended to get your system pumped when a septic professional recommends to after inspecting your system. They will be able to take measurements to determine if it is time to get it pumped.

Water, toilet paper, human waste, and soap for washing. 

It is not prohibited, however we do not recommend using a garbage disposal. If you must use it, we recommend minimizing the amount of food, oil, and grease going into your septic tank. Sink strainers can be a great alternative to using a garbage disposal.

If you are concerned about the status of your system, some signs that may indicate failure are:

• Fixtures are draining slowly
• The ground above the drain field is soggy and has unusually lush vegetation
• Sewage is backing up into the house
• Sewage is surfacing on the ground over the drain field or septic tank
• There is a strong sewage odor

Please contact a licensed septic professional if you suspect your system is failing or in need of a repair.

Please refer to our page on permit process steps.

Approved OSS applications are valid for 2 years from the date approved. Once the 2 years is up, you may renew for an additional 2-year period by following these steps: 

1. Within 30 days of expiration, you will need to have a designer or professional engineer submit a Renewal Application. You do not need to use the same designer you used for your original application. 
2. Pay the renewal fee. 
3. The Health Department will review and approve for renewal if everything looks good. 
4. You can continue renewing for 2-year periods, following steps 1-3 as needed. 

What happens if you miss the cutoff? A whole new application and new application fee must be submitted. Money-Saving Tip: The renewal fee is a lot less than a new app fee, so don’t miss the cutoff!

You will still need to contact a licensed septic designer. If the Application for an Individual Water Supply Site Inspection is submitted concurrently with the Application for an Onsite Sewage Disposal Permit, the fee is less than if it is submitted on its own

The Snohomish County Health Department investigates complaints and problems with septic systems in the county. Issues can be reported online or mailed to:

Environmental Health Division
Land Use Program
3020 Rucker Avenue
Suite 104
Everett, WA 98201-3900

Your complaint will remain anonymous, and you will receive a reply regarding the situation after the initial investigation is completed.

Please refer to the Guidelines for Cleaning Indoor Sewage Spills document.

State law requires that homeowners inspect and maintain their septic system to ensure it is functioning properly. An as-built drawing shows the location of your drain field, which is also useful for:

• Property owners doing landscaping or building
• Real estate professionals preparing for a purchase or sale
• Septic professionals doing maintenance or repair

• Year installed
• Property information
• Type and location of the septic system installed on the property

In general, the only information included is the as-built drawing, which is the final drawing of what your system looks like after installation. Additional information on the property’s septic system may be on file at the Snohomish County Health Department  offices.

The "Property Site Information" and "Property Owner Information" sections are from the Snohomish County Assessor’s Office and are updated on a routine basis. The "OnlineRME" and "Comments" sections are entered by the Snohomish County Health Department Land Use program. Attached scans are from the district’s files.

You can contact a licensed septic designer to submit a revised as-built that shows the correct locations of your septic system’s components.

The Washington Administrative Code (WAC) contains regulatory requirements for septic tank abandonment. The Snohomish County Health Department does not have additional regulations. Please reference this guidance document.

To appeal application decisions, please refer to chapter 1.20 Snohomish County Board of Health Code (SCBHC). An administrative appeal must be filed in writing with the Environmental Health Division Office within twenty-one (21) calendar days from the date of your application decision.

Download, complete, and save the "Request for Appeal" form to your computer/device.  Send an email, attaching your completed Appeal Request and supporting documents, to SHD-EHQ@snoco.org.

Environmental Health Specialists (EHSs) can enter your property for the purposes of reviewing your application and design or conducting a final inspection at any time per Snohomish County Board of Health Code (SCBHC) 1.05.080. They will knock to see if someone is home, notify you of their presence and reason for visiting, and request access to your property. However, if no one is home they will still proceed with their review/inspection. 

Visit our septic application turnaround times webpage to check your application status and see our current turnaround times.

On rare occasions, an easement may be required for your septic system. If this is required, note that it will need to be notarized and recorded with the county recording office and there is a fee to record documents. We have an example of an easement document available below.

On-Site Sewage System Easement Example

During the design phase, you may need to complete other requirements. For instance, if you are also seeking a building permit, the Department of Planning & Development Services (PDS) will let you know of things like land surveys, critical area reviews, wetland delineations, etc. that may need to be completed. There may also be things like property easements you need to sort out during the design process.

• Washington On-Site Sewage Association
• EPA Septic Systems
• Snohomish County Assessor
• OnlineRME