A plumber shows up with a van, a shirt with a logo, and a number that sounds about right — how do you know they're actually licensed, insured, and going to stand behind the work? A short list of questions asked before anyone touches a pipe separates a vetted pro from someone who'll leave you with a bigger problem than you started with. Ask these, get the answers in writing, and you'll have something solid to compare bids against instead of a gut feeling.
Is the Plumber Licensed and Insured?
Ask for the plumber's license number and where it's registered, then check it yourself against your state or local licensing board before you agree to anything. The FTC is blunt about this: "Consider only contractors who are licensed and insured. Check with your state or county government to confirm a contractor's license, and ask the contractor for proof of insurance."
Two kinds of coverage matter here. General liability insurance covers damage to your home during the job — a burst supply line, a flooded floor. Workers' compensation covers the plumber (or their crew) if someone gets hurt on your property. Without it, you could be on the hook. If you're weighing a licensed plumber against a handyman for a repair, see Should I Hire a Licensed Plumber or a Handyman? — licensing requirements and the risk of going unlicensed vary by the size of the job.
What Should Be in the Written, Itemized Quote?
A verbal number over the phone isn't a quote — it's a guess. Ask for a written estimate that itemizes labor, materials, and the total price, along with a description of the actual work and an expected completion date. That's the same standard the FTC recommends for any home repair estimate, and it's what lets you set one plumber's number against another's without comparing apples to oranges.
This matters most on jobs where scope can swing the price a lot — a leaking pipe repair might be a $150 fix or a wall-opening job depending on where the leak is, and an itemized quote is how you catch that difference before work starts, not after. If the number seems unusually low or high next to your other quotes, ask why — a big unexplained gap is worth a direct conversation before you sign.
What Warranty Should a Plumber Offer?
Ask directly: what's covered, for how long, and what do you need to do to make a claim? Reputable plumbers separate the labor warranty (their workmanship) from the manufacturer's warranty on parts (the water heater, the fixture, the pump), and both should be spelled out in writing before the job starts — not promised verbally and forgotten. A plumber who's vague about warranty coverage, or won't put it in the estimate, is telling you something about how they'll handle a callback if the fix doesn't hold.
What Else Should You Ask Before You Hire?
A few more questions round out the vetting:
- Have you done this specific type of job before? Drain cleaning, repiping, and water heater swaps call for different experience — ask about jobs like yours specifically, not just "how long have you been in business."
- Who will actually be on-site doing the work? Some companies send a different crew than the person who quoted the job. Confirm who shows up.
- Do you pull permits when the job requires one? Skipping a required permit can come back to bite you at resale.
- What's the payment schedule? A deposit tied to materials is normal; paying the full amount before work starts is not.
What Red Flags Mean You Should Walk Away?
Hesitation is the tell. If a plumber won't give you a license number, dodges questions about insurance, refuses to put the estimate in writing, or pressures you to sign the same day, treat that as your answer. The same goes for anyone who wants full payment upfront or shows up with no company name, no local address, and no way to verify who they are.
| Ask This | Why It Matters |
|---|---|
| "Can I have your license number?" | Lets you verify it with the state board before work starts |
| "Do you carry liability and workers' comp insurance?" | Protects your home and you if someone's hurt on-site |
| "Can I get this quote in writing, itemized?" | Makes bids comparable and catches scope surprises early |
| "What's your warranty on parts and labor?" | Tells you who pays if the repair fails later |
| "Who's actually doing the work?" | Confirms you're not getting an unvetted sub |
| "Do you pull permits for jobs like this?" | Signals whether the work will meet code |
What to Do About It
Write these six questions down and ask every plumber the same way, in the same order, so the answers are easy to compare. Call your state or local licensing board directly to confirm a license is active — don't just take a plumber's word for it. Get every quote in writing before you agree to anything, even for a job that sounds simple, like drain cleaning. And talk to more than one licensed plumber: when you have a couple of itemized quotes side by side, you know whether a price is fair instead of just hoping it is.
Mantel matches you with vetted, licensed plumbers in your area and gets you comparable quotes at no cost to you, so you're not doing this vetting alone.