Legal Nonconforming Septic Systems in Older Pierce County Homes

A note on sourcing: this page covers the general legal framework under Washington’s on-site sewage code (WAC 246-272A). We could not verify a Tacoma-Pierce County Health Department program page specifically dedicated to “nonconforming” systems, so treat this as the state-level legal foundation rather than a county-specific policy summary — and confirm your exact situation directly with TPCHD, since local health departments can apply additional rules on top of state code. Last checked July 2026.

Quick answer: a septic system that was properly approved and built to the code in effect at the time generally doesn’t have to be upgraded just because requirements have since changed — a common regulatory principle often called “legal nonconforming” or “grandfathered” status. But this isn’t unlimited: if the system later fails and needs a real repair or replacement (rather than a minor fix), current requirements typically come into play. The specifics for your property need to come from TPCHD directly.

What “Legal Nonconforming” Generally Means

Many older homes in Pierce County — particularly in established Tacoma and Lakewood neighborhoods — have septic systems that were installed decades ago, under different design and code requirements than exist today. In general regulatory practice, a system that was properly permitted and built under the rules in place at the time doesn’t automatically become illegal just because the code has since changed. This is sometimes called “grandfathering,” though the more precise term in most local health codes is legal nonconforming status.

Important: this is a general regulatory concept, not a specific guarantee about your property. Whether it applies, and exactly how, depends on your system’s history and TPCHD’s determination — not on this page.

The Real Distinction in Washington Code: Remediation vs. Repair

Definitions from Washington’s on-site sewage code, WAC 246-272A. Which category your situation falls into affects what’s required going forward — confirm directly with TPCHD before starting work.

This distinction matters because it affects what happens when an older system runs into trouble. A straightforward fix that restores a previously-working, previously-approved component generally falls under remediation. A more serious failure — one requiring relocation, replacement, or reconstruction — falls under repair, and is more likely to trigger current code requirements for whatever’s being rebuilt. Which category applies isn’t something a homeowner decides on their own; it’s determined through TPCHD’s review process.

What Commonly Affects Nonconforming Status

Speaking generally about how jurisdictions like this typically handle older systems (again, confirm specifics with TPCHD): nonconforming status is commonly reconsidered when a system fails and needs full repair or replacement, when a property’s use changes in a way that increases sewage flow beyond what the system was originally designed for, or when an owner voluntarily requests an upgrade. None of this is a guarantee of how Pierce County will treat any specific case — it’s simply the general pattern seen in on-site sewage regulation.

Start With Your Actual Record

Before assuming anything about your system’s status, find out what it was actually approved for. TPCHD’s as-built lookup tool at tpchd.org/asbuilt lets you search by address or parcel number for your system’s record drawing. If your record can’t be located that way, you can request a manual records search — TPCHD aims to respond within about 5 days, though a full search can take up to 60 days.

Before You Start Any Work

If you have an older system and are considering repairs, an expansion, or a remodel, it’s worth getting a professional evaluation and talking to TPCHD before work begins — not after. Understanding in advance whether your situation falls under remediation or repair (and what that means for your specific system) avoids surprises partway through a project.

Have an older system and not sure where it stands? Connect with a local licensed septic provider for an evaluation.