Plumbing permits in City of Mercer Island: fees, timeline & requirements (2026)
Everything you need to know about pulling a plumbing permit in City of Mercer Island, Washington — when one is required, what it costs, how long review takes, what documents are required, and which inspections you can expect. Cited to Apply via MyBuildingPermit.com..
Free lookup, no account needed — your lot polygon, zoning, setbacks and overlays, cited to City of Mercer Island's source.
When does a plumbing need a permit in City of Mercer Island?
WAC 51-56 (2021 UPC) requires plumbing permit for installation, replacement, or relocation of any plumbing fixture, water heater, or piping. Like-for-like faucet replacement is exempt.
How City of Mercer Island adopted this rule
The threshold comes from the state code (WAC 51.56), which City of Mercer Island adopts by reference in the provision quoted below.
“The 2021 Edition of the Uniform Plumbing Code (UPC), as adopted and amended by the State Building Code Council in WAC Chapter 51-56, as published by the International Association of Plumbing and Mechanical Officials, is adopted by reference with the following additions, deletions and exceptions. Provided, that Chapter 1, Administration, is not adopted and the Construction Administrative Code, as set forth in Chapter 17.14 MICC, shall be used in place of UPC Chapter 1, Administration. Provided, that Chapters 12 and 14 of the Uniform Plumbing Code are not adopted.”Source ↗verified 2026-04-29
Required submittals
- fixture count + DFU calc for repipes
- water heater specs
- sewer line plan if site work involved
Inspection sequence
- rough-in / pressure test
- final
Contractor specialties needed
plumbing
Who can do this work in City of Mercer Island?
Kolmo Construction is a licensed Washington general contractor — KOLMOL*753JS, active through April 10, 2027, bonded and insured — working throughout City of Mercer Island and King County. Kolmo prepares the drawings and submittals, files the plumbing permit with Apply via MyBuildingPermit.com., carries the project through review and inspections, and performs the construction. Call (206) 410-5100 for a City of Mercer Island plumbing quote.
Notes & caveats
From multi-jurisdiction tip sheet (Mercer Island): "Bathroom and kitchen fixture replacements without plumbing line modifications such as sinks and toilets" are exempt. However: "Tub and shower replacement does require a permit." Hose bibs and drinking fountains (per the same tip sheet) require a permit. Backflow prevention devices require a permit.
How to apply yourself
- 1. Confirm your parcel's zoning & overlays. Run an address lookup for your City of Mercer Island plumbing — we'll pull your specific lot polygon, zoning, setbacks, and any shoreline/ECA/historic overlays.
- 2. Assemble submittals (3).
- 3. Submit through the city portal: Apply via MyBuildingPermit.com. ↗
- 4. Track review. Respond to reviewer comments promptly.
- 5. Pay issuance fees (Plumbing permit fees are set by fixture count in the city's fee schedule.) and pick up the permit. Inspection card travels with the job.
Or have Kolmo do it
We pull plumbing permits in City of Mercer Island every month. We prepare the drawings and submittals, file with Apply via MyBuildingPermit.com., handle reviewer comments, and build the project.
Licensed WA general contractor KOLMOL*753JS · bonded & insured
Plumbing permits in City of Mercer Island — FAQ
When does a plumbing need a permit in City of Mercer Island?
WAC 51-56 (2021 UPC) requires plumbing permit for installation, replacement, or relocation of any plumbing fixture, water heater, or piping. Like-for-like faucet replacement is exempt.
How much does a plumbing permit cost in City of Mercer Island?
Current fee per the City of Mercer Island fee schedule: Plumbing permit fees are set by fixture count in the city's fee schedule.. Plus ancillary plan-review/tech-surcharge fees per city schedule.