Questions to Ask Before Hiring a Plumber
Ten questions that separate licensed, insured professionals from contractors who will leave you with a bigger problem than the one you started with.
Before hiring any plumber, ask for their state license number, proof of liability and workers' compensation insurance, a written itemized estimate, permit responsibility, and their workmanship warranty. Those five questions eliminate most bad contractors.
| What to Verify | How to Verify It | Minimum Acceptable |
|---|---|---|
| State plumbing license | State licensing board lookup (online) | Current, matches company name |
| General liability insurance | Certificate of Insurance with your address | $1M+ per occurrence |
| Workers' compensation | Certificate of Insurance, current dates | Statutory limits in your state |
| Permit responsibility | Written on the estimate | Plumber pulls permits, not homeowner |
| Workmanship warranty | Written on invoice or estimate | 30–90 days on labor |
The same vetting logic applies across trades. See our guides on questions to ask a cleaning company and questions to ask an electrician before hiring.
Why Vetting a Plumber Before Hiring Matters
Plumbing failures are among the most expensive home repair categories. A burst pipe behind a wall can cause tens of thousands of dollars in water damage. An improperly installed water heater is a safety hazard. Work done without permits can prevent a home from selling or require costly remediation.
The contractor you hire has access to the systems behind your walls, under your floors, and connected to your gas supply. The ten questions below are not bureaucratic formalities — they are the fastest way to identify whether the person doing that work is qualified, accountable, and insured.
For cleaning trades, the same verification process applies — see our guide on how to hire a cleaning service for a parallel framework.
10 Questions to Ask Before Hiring a Plumber
Ask these before any work begins — not after you've already agreed to let someone start.
Are you licensed in this state, and can I have your license number?
Plumbing is a licensed trade in every U.S. state. A license confirms the plumber passed a state exam and meets minimum competency standards. Ask for the number so you can verify it yourself — not just their assurance that they're licensed.
Go to your state's contractor licensing board website and look up the number before work starts. The name on the license should match the company name on your invoice.
Do you carry general liability and workers' compensation insurance?
General liability covers property damage during the job — a pipe burst, a wall damaged during access. Workers' comp covers the crew if someone gets hurt on your property. Without it, you may be liable for injuries that happen in your home.
Ask for a Certificate of Insurance before work starts. The certificate should name your address as the job site and show current policy dates. A policy that expired last year is not coverage.
Will you pull permits for this job?
Any plumbing work that modifies supply, drain, or gas lines requires permits in most jurisdictions. Permitted work is inspected — meaning a third party verifies it was done correctly. Unpermitted work can void homeowner's insurance and create problems at resale.
If a plumber offers to skip permits to save you money or move faster, treat it as a disqualifier. The permit fee is typically $50–$200. The liability of unpermitted work is much larger.
Can you give me a written, itemized estimate before starting?
A verbal estimate is not an estimate — it's a conversation. A written estimate that itemizes labor, materials, and permit fees separately gives you a clear baseline. It protects you if the final invoice differs significantly from what was discussed.
Compare written estimates across multiple plumbers on the same scope of work. If one estimate is dramatically lower, ask what's different — not just accept that you found a deal.
Is this flat-rate pricing or time-and-materials?
Flat-rate pricing means a fixed cost for a defined task regardless of how long it takes. Time-and-materials means you pay the actual hours plus the cost of parts. Both are legitimate — but you need to know which one you're agreeing to before work starts.
For clearly defined jobs (water heater swap, drain clearing), flat-rate pricing is usually better for you. For diagnostic or unknown-scope work (finding a hidden leak), time-and-materials is more appropriate because the scope can't be defined upfront.
What does your warranty cover, and how long does it last?
Workmanship warranties cover defects in the installation itself — if a fitting leaks because it wasn't seated correctly, that's the plumber's responsibility. Materials warranties cover the parts. A plumber who won't commit to a workmanship warranty is telling you something about how they stand behind their work.
Ask specifically: if the repair fails or leaks within 30 days, who pays for the return visit? Get the answer in writing on the estimate or invoice.
How long have you been doing this type of work specifically?
Plumbing specialties exist — a plumber experienced in residential service work may not have experience with commercial systems, gas lines, or radiant heating. A company that handles drain clearing every day knows that problem better than one that does it occasionally.
Ask about their experience with your specific problem or project type, not just how long they've been licensed. Years of license don't equal years of relevant experience.
Who will actually be doing the work — you or a subcontractor?
Some plumbing companies sell jobs and then hand them off to subcontractors. The sub may not carry the same insurance, may not know the job history, and may not share the same quality standards. You deserve to know who is setting foot in your home.
If subcontractors are used, ask whether they're licensed and insured under a separate policy, and ask to see that certificate too.
Can you provide references from similar jobs in the past 12 months?
References from recent, similar work tell you what this plumber is doing right now — not what they were doing three years ago under different ownership or management. A plumber who can't provide any references has a gap worth questioning.
When you call references, ask specifically: Did the work match the estimate? Was the site clean when they left? Did anything fail or need a callback?
What's your policy if the scope changes after work begins?
Plumbing jobs often reveal secondary problems once walls are open or pipes are exposed. A written change-order policy means any scope additions get your written approval before the cost is added. Without it, a $400 job can become a $1,200 surprise.
Ask the plumber to walk you through what happens if they find something unexpected. A professional answer is: we stop, show you what we found, give you an updated estimate, and wait for your approval. Any other answer is a red flag.
Red Flags to Watch For
These patterns — regardless of how confident or professional the contractor seems — warrant walking away.
Door-to-door solicitation after a storm or pipe event
Legitimate plumbing companies don't canvas neighborhoods after weather events. If someone knocks on your door offering to check your pipes 'for free,' decline.
Cash-only or no-receipt policy
A company that won't provide a written invoice cannot be held accountable for what they charged or what work was done.
Pressure to decide immediately or lose a 'special price'
Urgency tactics are a manipulation technique. A legitimate plumber gives you time to compare estimates. Emergencies aside, no reputable company requires you to sign on the spot.
Refusal to provide a license number for verification
If a plumber says their license is 'on file' but won't give you the number to verify, that's a reason to look elsewhere.
No local presence or physical business address
A plumbing company with no verifiable local address and only a mobile phone number is difficult to hold accountable if something goes wrong after the job.
When Permits Are Required for Plumbing Work
Permit requirements vary by jurisdiction, but the general rule applies consistently across most U.S. municipalities: any work that modifies the plumbing system beyond a direct like-for-like fixture replacement requires a permit.
Usually Requires a Permit
- ·Water heater installation
- ·Pipe rerouting or relocation
- ·New bathroom or kitchen addition
- ·Sewer line repair or replacement
- ·Gas line work
- ·Water service line replacement
Often No Permit Required
- ·Faucet replacement (same location)
- ·Toilet replacement (same footprint)
- ·Drain clearing
- ·Showerhead replacement
- ·Minor leak repair on accessible pipe
- ·Sink replacement (same configuration)
When in doubt, call your local building department before hiring. Permit requirements are public information — they'll tell you whether the job you're describing requires one. Don't rely on the contractor's judgment on this question alone.
Frequently Asked Questions
What questions should I ask a plumber before hiring?
Ask for their state license number, proof of liability and workers' comp insurance, a written itemized estimate, whether they pull permits, and what their warranty covers. These five questions eliminate most problematic contractors before work begins.
How do I verify a plumber's license?
Ask for the license number and verify it on your state contractor licensing board's website. Most states have a free public lookup tool. Confirm the name on the license matches the company you're hiring.
Should a plumber pull permits for my job?
Yes, for work beyond simple fixture replacements. Any work that alters supply, drain, or gas lines requires permits in most jurisdictions. A plumber suggesting you skip permits to save time or money is a red flag.
What's the difference between a licensed plumber and a handyman for plumbing work?
A licensed plumber passed a state exam and can pull permits for code-governed work. A handyman may handle minor tasks without a plumbing license in some states, but cannot do supply, drain, or gas line work that requires permits.
How should a plumber price a job?
A plumber should provide a written estimate that breaks out labor, materials, and permit fees separately. Flat-rate pricing works for defined tasks; time-and-materials is appropriate for diagnostic or unknown-scope work.
Jason Ellis
Home Services Research Lead, HomePros Directory
I've spent eight years evaluating home service contractors — reviewing licensing records, insurance certificates, and customer outcomes across cleaning, trades, and repair categories. The questions in this guide are the ones I've watched homeowners skip, and the problems that resulted are the ones that cost the most to fix.
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