What are the most common plumber scams?

Five plumber scams account for most consumer complaints to state plumbing boards. Each has a tell and a defense.

1. Whole-home repipe off a single failed fitting. The plumber arrives to fix a slab leak, a single corroded coupling, or a pinhole leak. After 20 minutes of inspection, they announce that "all your pipes are corroded" and the entire house needs to be repiped in PEX or copper — typically $15,000-$30,000. Sometimes the pitch is real (Kitec, Quest Polybutylene, certain galvanized eras between 1900-1970 are genuinely time-bombs), but the scam is to pitch repipe off systems that have decades of life remaining. Defense: get a second quote. Ask for water-quality test results, sample-pipe inspection at multiple locations, and pipe-material documentation. Real repipe pitches are evidence-based.

2. Sewer-line full replacement without a video scope. The plumber announces that your main sewer line is collapsing or root-invaded and needs full replacement ($5,000-$25,000). The defense is non-negotiable: require a video scope you can watch in real-time, recorded for your records. Get a second opinion from a different plumber with their own camera. The clay-pipe-needs-replacing pitch is one of the highest-dollar plumbing scams, and trenchless lining is often a viable alternative at half the cost.

3. "Your hot water heater is about to fail." Sometimes true (12+ years old, leaking, sediment evidence), often manufactured. The plumber points to a drip pan, sediment in a flush, or a "high" inlet pressure and pitches a $2,500-$5,000 tank or tankless replacement. Defense: ask for the manufacturer date plate (water heaters last 8-15 years; an 8-year unit isn't "about to fail"), the failure indicator (drip pan stain old or fresh?), the T&P discharge history, the sediment flush result, and the manufacturer warranty status. If the unit is under warranty, the manufacturer pays for replacement.

4. Pre-emptive water shutoff during quoting. The plumber arrives, shuts off the main, and refuses to turn it back on until you sign for emergency work. This is leverage extraction — you can't function without water, so you sign whatever's in front of you. A real plumber gives you the option to live overnight without water and consider the quote. Defense: turn the water back on yourself (every house has a main shut-off), and get a written quote with 24-hour decision time.

5. Upfront-deposit phoenix. The plumber quotes $4,000 for a sewer-line repair, takes a $2,500 deposit (well above the legal 10%/$1,000 California cap), and disappears. Defense: cap deposit at the legal limit, pay by credit card or check for paper trail, and run Groundcheck before paying.

6. (Bonus) Gas-line "leak" upsell. The plumber finds a "small gas leak" on a routine call and pitches a full gas-line replacement. Defense: require a soap-bubble test or electronic gas detector demonstration with you watching, and call the gas utility — they will come out for free and pressure-test the line. Most utilities have free leak detection because the safety stakes are real.

7. (Bonus) Drain cleaning that converts to "main line replacement." A $200 drain clearing call becomes a $5,000-$25,000 main line replacement pitch. Defense: video scope must be part of the diagnosis, and the scope footage must be reviewable.

Groundcheck (earthmove.io/trust) verifies the state plumbing license, qualifying party name, prior disciplinary actions, mechanics-lien history, and phoenix-company patterns across the state plumbing board, Secretary of State, court records, OSHA, and BBB. It does not verify the technical accuracy of a specific diagnosis — get a second quote on any job over $5,000.