How to hire a plumber: skills, tests, interview questions and pay

Knowing how to hire a plumber comes down to five things: choosing the right license level for the work, checking real plumbing skill before the interview, asking questions that expose how a candidate diagnoses problems, verifying the license and background, and paying at or above the local market. Get those right and you cut the risk of leaks, failed inspections and repeat call-backs.

TL;DR:

• Employers hiring plumbers for a facilities team, a hospital, a property portfolio or a plumbing business. A short section at the end covers homeowners hiring for a single job.
• Apprentice, journeyman and master. Hire the level that fits the work, and check your state plumbing board for local rules.
• Seven steps, from defining the role to offer and onboarding.
• Plumbing code, diagnosis, pipe joining, reading drawings, safety and customer service. Use an online test for all applicants, then a paid practical task for finalists.
• The US Bureau of Labor Statistics reports a median wage of $63,800 a year, or $30.67 an hour, in May 2025. Show the pay range in the job post.
• Check the license, driving record, background and references before the offer.

What does a plumber do?

A plumber installs, maintains and repairs the pipes, fixtures and appliances that carry water, waste and gas through a building. Day to day, that means diagnosing leaks and blockages, fitting new supply and drain lines, installing water heaters and fixtures, and making sure the work meets the local plumbing code so it passes inspection.

Plumbing jobs fall into three broad types, and the type changes who you should hire:

• Service and repair plumbers work alone in occupied homes and buildings. Diagnosis, customer communication and driving matter as much as pipework.
• New construction plumbers rough in and finish systems on building sites, working from drawings alongside other trades.
• Commercial and facilities plumbers keep hospitals, offices, hotels and campuses running, often on call, with larger pipe sizes, backflow devices and stricter safety rules.

If the role is mostly industrial piping, steam or process lines, you are hiring a pipefitter rather than a plumber. Our guide to hiring a plumber pipefitter covers that role.

What are the plumber license levels?

Plumber license levels in most US states run from apprentice to journeyman to master. According to the US Bureau of Labor Statistics, most states and some localities require plumbers to be licensed, usually after 2 to 5 years of experience and an exam, and most plumbers learn the trade through a 4- or 5-year apprenticeship.

Exact rules vary by state and city, so check your state plumbing board before you write the job post. Some states also issue separate gas, backflow or medical gas endorsements, which matter for hospitals and commercial buildings.

How to hire a plumber step by step?

Hiring a plumber works best as a short, fixed sequence that every candidate goes through. The sequence below keeps the process fast enough that good plumbers do not take another offer while you are still reading resumes.

1. Define the role: Pick the work type (service, construction or facilities), the license level, on-call needs and whether the job needs a company van.
2. Write the job description. Lead with pay, schedule and license level. Plumbers compare offers on these first.
3. Source candidates: Use apprenticeship programs, union halls, trade schools, referrals and job boards at the same time.
4. Screen skills first: Send a short online plumbing test before any interview so you only spend time on people who know the code and the techniques.
5. Interview with structure: Ask every candidate the same technical and situational questions and score the answers against a simple scorecard.
6. Run a practical check and verify: Give finalists a paid hands-on task or ride-along, then verify the license, driving record and references.
7. Offer and onboard: Make a written offer quickly, then pair the new hire with an experienced plumber for the first weeks.

Pro tip: Put the pay range in the job post. Plumbers are in short supply, and a hidden pay range is one of the fastest ways to lose experienced applicants to a competitor who shows theirs.

What skills should you look for in a plumber?

Plumbers need a mix of technical skill, safety habits and customer skills. Technical skill decides whether the work passes inspection; the other two decide whether customers and colleagues trust the plumber on their own.

For service roles, weight customer service and reliability higher. For construction roles, weight drawings and installation higher. For hospital and facilities roles, weight safety and code knowledge higher.

How do you test a plumber's skills before hiring?

Testing a plumber's skills works best in two stages: a short online test for everyone who applies, then a hands-on check for the few finalists. The online test filters out people who do not know the code or the basics, so the practical check, which costs time and money, only goes to strong candidates.

• Online plumber test: A timed knowledge test on codes, diagnosis and techniques. It takes minutes, works on a phone and gives you a score you can compare across every applicant and every branch.
• Scenario questions: Describe a real job, such as low water pressure on one floor only, and ask how they would find the cause. Strong candidates ask questions before they reach for a tool.
• Paid practical task: Ask finalists to complete a short task in your workshop: join copper and PEX, set a trap, or find a planted fault. Pay them for the time.
• Ride-along. For service roles, a half day with a senior plumber shows how the candidate talks to customers and handles the van, the paperwork and the clock.

Proof of past work, such as photos of installs, helps too, but treat it as a talking point rather than evidence. You cannot tell who did the work from a photo.

Where can you find qualified plumbers?

Qualified plumbers are easiest to find through the training and trade networks they already belong to, not only through job boards. With most experienced plumbers already employed, you usually need to reach them where they learn and meet.

1. Apprenticeship programs: Sponsor apprentices or partner with a local program. It is slower, but it builds your own supply of licensed plumbers.
2. Union locals: The United Association represents plumbers, pipefitters and other pipe trades and runs apprenticeship and training through its local unions.
3. Trade schools and community colleges: Recruit from plumbing and building services programs before students graduate.
4. Trade associations: Groups such as the Plumbing-Heating-Cooling Contractors Association run training and events where you can meet working plumbers.
5. Related trades: Pipefitters, HVAC technicians and maintenance technicians often have the mechanical base to train into plumbing roles.
6. Employee referrals: Plumbers know other plumbers. A referral bonus is usually cheaper than a job-board campaign.
7. Job boards and social media: Post on general and trade job boards, and share the post in local trade groups.

What should a plumber job description include?

A plumber job description should state the pay range, license level, work type, schedule and on-call needs in the first lines, followed by the main duties and requirements. You can start from our plumber job description template and adapt it with the outline below.

• Job title and license level: for example, "Journeyman plumber, commercial service".
• Pay and benefits: hourly range, overtime and on-call pay, tools or tool allowance, van, health cover and training.
• Schedule: shift pattern, weekends and on-call rotation.
• Main duties: install, maintain and repair water, drain and gas systems; diagnose faults; keep job records; follow code and safety rules.
• Requirements: state license level, years of experience, valid driver's license if the role uses a company vehicle, and any endorsements such as backflow testing or medical gas.
• How to apply: a short application and a link to the skills test, so candidates know what comes next.

What interview questions should you ask a plumber?

Interview questions for a plumber should test how candidates diagnose problems, how they work safely and how they deal with customers. Ask every candidate the same questions and score each answer from 1 to 5 against what a good answer covers.

Technical questions

1. Walk me through how you would find the cause of low water pressure on one floor of a building.
2. How do you decide between copper, PEX and CPVC for a repair or a new run?
3. A drain keeps clogging after you clear it. What do you check next?
4. How do you make sure a new install will pass inspection the first time?
5. When is a backflow preventer required, and how do you test one?

Safety questions

1. Tell me about the last time you stopped a job because something was unsafe.
2. What do you do before working on a gas line?
3. How do you protect yourself and others when soldering or brazing in an occupied building?

Customer and teamwork questions

1. How do you explain a costly repair to a customer who did not expect it?
2. Tell me about a job where the customer was unhappy. What happened, and what did you do?
3. How do you coordinate with electricians or HVAC technicians on a shared job?

Work style and fit questions

1. How do you plan your day when you have several service calls and one turns into a bigger job?
2. How do you keep up with code changes and new products?
3. How do you feel about on-call shifts, and how have you handled them before?
4. Why do you want to work for us rather than run your own jobs?

Key takeaway: Good answers are specific. A strong plumber names the tools, the order of checks and the code rule. A weak one talks in general terms about "fixing whatever is wrong".

How much does it cost to hire a plumber?

The cost to hire a plumber as an employee starts with wages. The BLS Occupational Outlook Handbook reports a median annual wage of $63,800, or $30.67 an hour, for plumbers, pipefitters and steamfitters in May 2025. Pay varies widely by state, city, license level and overtime.

Demand keeps pushing that number up. BLS projects employment of plumbers, pipefitters and steamfitters to grow 7% from 2025 to 2035, with about 42,000 openings a year. Across construction as a whole, Associated Builders and Contractors estimates the industry must attract about 349,000 net new workers in 2026, mostly to replace people who retire.

Beyond wages, budget for:

• Overtime and on-call pay.
• Tools, or a tool allowance, and protective equipment.
• A van, fuel and insurance for service roles.
• License renewal fees and continuing education.
• Recruiting costs: job ads, referral bonuses, assessments and the hours your team spends interviewing.

The most expensive cost is a wrong hire. A plumber who fails inspections or upsets customers costs you call-backs, rework and reputation, which is why the skills check and verification steps come before the offer.

How do you verify a plumber's license and background?

Verifying a plumber's license takes a few minutes on your state plumbing board or licensing agency website, where you can search by name or license number and see the level, status and expiry date. Check it before the offer, not after the start date.

• License: confirm the level matches the job, the license is active, and any endorsements (gas, backflow, medical gas) are current.
• Driving record: for roles that use a company van, check the driver's license and driving record, with the candidate's consent.
• Background check: in the US, if you use a background check company, the FTC guidance for employers says you must tell the candidate in a stand-alone written notice and get their written permission first.
• References: ask past supervisors about quality of work, call-backs, punctuality and how the plumber treats customers.

Hiring a plumber for a single job instead?

Homeowners and small offices hiring a plumber for one repair need a lighter version of the same checks. A licensed, insured plumber with a written quote protects you if the work fails or someone is hurt on your property.

• Check the license on your state board's website.
• Ask for proof of liability insurance.
• Get two or three written quotes that list labour, parts and any call-out fee.
• Ask whether the job needs a permit and who pulls it.
• Read recent reviews and ask how they guarantee the work.

How can Testlify help you hire plumbers?

Testlify helps hiring teams screen plumbers on skill before the interview, so recruiters and supervisors only meet candidates who already know the trade. That matters most when you hire across many sites or need to fill roles quickly.

• Plumber test: the Testlify plumber test takes 10 minutes and covers plumbing codes and regulations, diagnosing plumbing issues, and plumbing techniques and procedures. It is available in Dutch, English, French, German and Spanish.
• Related tests: combine it with mechanical aptitude, safety awareness or customer service tests from the test library of 3,500+ tests, or use the plumber pipefitter test for piping roles.
• Fair, cheat-resistant tests: 20+ proctoring checks such as webcam snapshots and full-screen enforcement keep scores honest when candidates test from home.
• One-way video interviews: video interviews let candidates answer your scenario questions between jobs, without scheduling a call.
• ATS sync: results flow into 100+ ATS and HRIS integrations so your team works in the tools it already uses.

Testlify is credit-based, so you pay only when a candidate starts an assessment, and you can start with a 7-day free trial with no credit card. To see it on your own plumber roles, book a demo.

FAQ: what else should you know before you hire a plumber?