Septic-to-Sewer Conversion in Pierce County: What Homeowners Need to Know

Sourced from official Tacoma-Pierce County Health Department (TPCHD) and Pierce County Planning & Public Works program information — last checked July 2026.

Quick answer: converting a property from septic to public sewer in Pierce County requires approval from both Tacoma-Pierce County Health Department and Pierce County Planning & Public Works before a sewer permit is issued. You must apply to decommission your septic tank before any pumping happens. If your home was built with an interim septic system on a “dry lines” street, you’ll get a 180-day window to connect once public sewer service reaches you.

Why This Comes Up: “Dry Lines” Neighborhoods

Some Pierce County developments were built before public sewer service reached them. In these cases, the county required builders to install interim on-site septic systems while also laying the sewer mains that would eventually connect the neighborhood — these are called “dry lines,” since the pipe is in the ground but not yet connected to the public system. There are currently 31 such developments in the Pierce County Sewer Service Area. Once sewer service becomes available, the county notifies affected property owners, and homeowners get 180 days (6 months) to complete the connection and properly decommission their septic system.

The Conversion & Decommissioning Process

The single most important rule: your septic decommissioning application must be submitted to the Health Department before any septic tank pumping occurs — not after. Applications are submitted through TPCHD’s online permit system under “On-Site Sewage” → “Septic Tank Decommissioning.” A certified O&M firm approved for pumping must remove the septage, and a site plan showing the decommissioned tank’s location is filed along with the applicable fee. Once your sewer connection is approved and the tank is properly decommissioned, you’ll schedule a sewer inspection and upload your Septic/Pump Tank Decommissioning Certificate to your online application (or email a copy).

Financial Help: Tacoma’s Septic Amnesty Program

If you’re within City of Tacoma limits, converting within two years of public sewer becoming available to your residence qualifies you for a 50% reduction in sewer LID assessment fees or charges-in-lieu-of-assessment — up to a maximum of $10,000. This offer expires two years after sewer becomes available, so it’s worth acting on sooner rather than later. Tacoma’s Environmental Services Sewer Conservation Loan Program also offers low-interest loans for side sewer rehabilitation or reconstruction projects within city limits.

What Happens If You Don’t Convert

Continued use of an on-site septic system after public sewer becomes available — without completing the required decommissioning and connection process — runs against Pierce County’s sewer use code. Beyond the compliance risk, waiting past the amnesty window (if you’re in Tacoma) means losing access to a meaningful fee reduction for no real benefit.

Notified that sewer is available to your property, or not sure where to start? Connect with a local licensed septic provider.