Hiring a plumber: what to ask and how to check a license

Plenty of plumbing is homeowner-friendly. A running toilet, a dripping faucet and a slow drain are often fixed with a few parts and some patience. A plumber earns their fee on the jobs where a mistake means water damage inside your walls, sewage in your house or a gas leak.

This page explains what a plumber does, which jobs to hand off, how to check a license and how to get a quote that holds up.

What a plumber does, and doesn't do

Plumbers install and repair the pipes, fixtures and appliances that bring water in and carry waste out. Common calls include:

Leaks under sinks, behind walls and at the water heater
Clogs a plunger or drain snake won't clear, especially in the main sewer line
Replacing or repairing water heaters
Low water pressure across the whole house
Installing toilets, faucets, sinks, tubs and shutoff valves
Frozen or burst pipes

Depending on where you live, some plumbers also do gas piping, and some don't. Plumbers usually don't handle the electrical side of appliances, drywall repair after a leak, or the appliance itself on a dishwasher or washer. For those, you may need an electrician, a handyman or an appliance repair technician.

Plumbing jobs you shouldn't DIY

Gas lines of any kind. That includes connecting a gas water heater, dryer or range. Never DIY gas piping.
Water heater replacement. It involves gas or high-voltage power, venting and a pressure relief valve. Many cities require a permit.
Main sewer line problems. If several drains back up at once, the problem is likely in the main line.
Moving or adding supply or drain lines. Slope, venting and code rules matter, and mistakes hide inside walls.
Burst pipes inside walls or ceilings. Shut off the water and call.

Before calling, it's worth trying the easy fixes: see fix a running toilet, fix a leaky faucet, unclog a drain without chemicals, low water pressure and no hot water.

Plumbing licensing

Most states license plumbers, plumbing contractors or both. Some license at the state level, and some leave it to cities or counties. Licensing usually requires work experience and an exam, and many places also require a permit and inspection for bigger jobs like water heaters and repiping.

To check a license, find your state's licensing board (search your state name plus "plumbing license lookup"), then search by the plumber's name, company or license number. Confirm the license is active and covers the kind of work you need.

In South Carolina, for example, the Department of Labor, Licensing and Regulation (LLR) licenses residential plumbing contractors through its Residential Builders Commission, and you can search any license with LLR's online Licensee Lookup. Other states organize this differently, so check your own. Our guide to checking a contractor license has step-by-step help.

What drives the cost

Timing. Nights, weekends and holidays usually cost more.
Trip or diagnostic fee. Many plumbers charge to come out, sometimes credited toward the repair.
Access. A pipe behind finished tile or under a slab takes far longer to reach than one under an open sink.
Parts. Fixture quality, water heater type and pipe material all matter.
Permits. Required for some jobs, and the fee is passed on.
Age of the house. Older pipes and odd fittings can turn a simple swap into a bigger job.

Questions to ask before hiring

What's your license number, and is it active for this work in our state or city?
Do you carry general liability insurance and workers' compensation? Can I see a certificate?
Is there a trip or diagnostic fee, and is it applied to the repair?
Do you quote a flat price or charge by the hour?
Will this job need a permit, and will you pull it?
What warranty do you give on parts and labor?
If you find something else once the wall is open, how will you tell me and price it?

How to describe the problem for an accurate quote

Plumbers can price a job much more accurately when you give them the details up front:

Where and what. "Kitchen sink, water drips from the cold supply line under the cabinet."
When it happens. Only when the dishwasher runs? Only after a shower? All the time?
How bad. A slow drip, a steady stream, or water on the floor.
What else is affected. One drain or several? Hot water only, or both?
Equipment details. For a water heater, the brand, model, gas or electric, and the age from the label.
Photos and video. A short clip of a leak or a gurgling drain helps a lot.
What you've done. "Shut off the valve under the sink; leak stopped."

Ask for a written estimate before the work starts. For larger jobs, get more than one; our guide to comparing quotes shows you how.

After the job is done

Before the plumber leaves, run the water and check the repair yourself. Look under the sink or around the fixture with a flashlight and a dry paper towel; even a slow drip will show. If a permit was pulled, ask when the inspection is scheduled and keep the paperwork. Hold the final payment until the work is done and you're satisfied, as the FTC advises.

Keep the invoice with the parts list and warranty terms. If the same leak returns in a few weeks, call the same plumber first. Most will come back under their workmanship warranty.

If you rent, call your landlord or property manager before you call a plumber. Repairs to the building's pipes and fixtures are usually the landlord's responsibility, and many leases require you to report leaks right away.

Next steps

Not sure if it needs a plumber? Try the fix-or-call quiz. When you're ready, read how to hire a contractor, or send a free match request to hear from local plumbers.

Common questions

What counts as a plumbing emergency?

Water you can't stop, sewage backing up into the house, no water at all, or any smell of gas near a water heater or gas appliance. For water, shut off the main valve first. For gas, leave the house and call the gas utility or 911 from outside.

Do plumbers need a license?

Most states license plumbers or plumbing contractors, and many cities require permits for work like water heater replacement. Look up the license number with your state licensing board before work starts.

Can a plumber work on my gas line?

In many areas licensed plumbers or gas fitters handle gas piping, but rules vary by state and city. Ask the plumber whether they are licensed for gas work where you live, and never attempt gas line work yourself.

Should I rent or call my landlord first?

If you rent, tell your landlord before calling a plumber. Plumbing repairs are usually the landlord's job, and many leases require you to report leaks promptly.