#1 · MERCER ISLAND
Every plumber below is ranked by real Google review data — score weighted by volume — with no paid placements. See exactly how the ranking works →
Mercer Island note: few plumbers are based in Mercer Island itself — the ranked companies below include pros based nearby in Seattle who serve Mercer Island.
Rating data from public Google Business listings, 2026-08-07. Rankings computed by review score weighted by volume — the formula is public. Run one of these companies? Claim your listing (free, never affects rank).
Rankings combine each company's Google review score and review volume — a 4.9 across hundreds of reviews outranks a 5.0 across four. No company can pay to appear or to move up; the same formula applies in every city we cover.
Yes — always. Washington requires contractors to be licensed, bonded, and insured. Ask for the company's L&I contractor number and check it at lni.wa.gov before work starts. It takes two minutes and filters out the horror stories.
No. Call any company above and you're calling them directly — their real number. We never collect or sell your contact details, and no contractor pays us for placement.