How to hire a plumber (job description, interview questions, screening workflow)

A burst pipe doesn't wait for a supervisor to sign off. Neither does the decision your plumber makes at 11pm about whether to cut into a wall. At a small plumbing business you're rarely on the job with them, so the hire lives or dies on judgment a resume can't show: whether they trace a leak to its source instead of re-caulking every joint until one stops dripping, whether they test a backflow preventer instead of assuming it's fine, and whether they tell a homeowner the truth about a repair that costs more than expected. Those calls come back to your company's name, not theirs. This guide screens for judgment and discipline under no supervision, not for a certificate.

What a plumber actually does at a small plumbing business

At a large plumbing company or a national service brand, a plumber works off a dispatch board set by a call center, backed by a service manager, a warehouse of parts, and a team that handles permits and paperwork. At a small plumbing business with a handful of trucks, the plumber is often the entire job. They diagnose the problem, decide what's actually required to fix it to code, explain the cost to the homeowner or general contractor standing in the kitchen, and drive to the next call without anyone coordinating it for them.

That difference changes what the role actually requires. A plumber at a small shop needs technical skill plus the judgment to make calls a service manager or a foreman would normally make at a bigger company: what to quote on the spot, when to call the owner before opening a wall that's worse than expected, how to push back on a GC who wants to skip a permit. There's less backup if something goes sideways on a job, and the stakes are real. A misjudged diagnosis costs money. A missed step on a gas line or a backflow preventer can hurt someone or flood a house.

The core responsibilities, in practice:

• Installing, maintaining, and repairing water supply, drain, waste, and vent systems in residential and light commercial buildings
• Diagnosing leaks, clogs, and pressure problems methodically, often solo and without a second opinion available on-site
• Reading blueprints and plumbing codes, and running pipe to match them
• Following code requirements, including backflow prevention and venting, and pulling the necessary permits, even when a customer or GC would rather skip the paperwork
• Handling gas line work and water heater installs safely, where licensed to do so
• Explaining the problem, the fix, and the cost to the customer or GC in plain language, before starting work
• Managing their own truck stock of fittings, pipe, and common parts
• Representing your company directly. For a lot of customers, the plumber at their door is the only interaction they'll ever have with your business

If you're a small plumbing contractor, your plumbers are your reputation and your liability at the same time. A homeowner or GC remembers whether the work was done to code, whether the plumber was upfront about cost, and whether they left the job site, and the house, in the shape they found it. That's worth naming when you post the role, because it's a different pitch than "plumber wanted."

Job description you can post today

Copy this, then adjust the specifics (your hours, your pay, your service area) to match your company.

Plumber
[Company name] is looking for a plumber to join our team of [X] trucks. You'll work independently on residential and light commercial jobs, diagnose and repair plumbing systems, and represent our company directly to the customers and contractors you work with.

What you'll do
Install, diagnose, and repair plumbing systems, including water supply, drain, waste, and vent lines, fixtures, and water heaters. Read blueprints and work to code on every job, including backflow prevention and venting requirements. Handle gas line work safely where licensed to do so. Explain the problem and the cost to the customer or GC clearly, before you start work. Keep your truck stocked and your paperwork current, including permits where required.

What we're looking for
A current journeyman or master plumber license, active and in good standing with your state or local licensing board. A valid driver's license with a clean record. Comfort working independently, without a service manager walking you through every call. Strong communication with customers and GCs, especially when the news isn't good.

Schedule
[Insert hours, e.g. Monday-Friday, 7am-4pm, with occasional emergency or on-call work]

[Insert pay, per your company's policy and any applicable state salary transparency requirements]

11 interview questions, and what a good answer sounds like

1. Walk me through how you'd track down a leak in a wall or under a slab, on a house you've never been in before.

You're checking for an actual troubleshooting sequence, not a guess. A strong answer moves in order: check the obvious fixtures and connections first, isolate sections of the system to narrow down where the water's actually coming from, use a moisture meter or listening equipment if it helps, and confirm before cutting into anything. A candidate who jumps straight to "I'd just open up the wall and look" without a process is telling you they'll turn a small repair into a big one on your dime, and on this trade a wrong guess means a homeowner's wall or ceiling gets opened for nothing.

2. What's a backflow preventer, and when do you test or install one?

This should come out specific, not vague. A strong answer explains that a backflow preventer stops contaminated water from siphoning back into the clean water supply, names situations that require one (irrigation systems, boilers, certain commercial connections), and knows whether their jurisdiction requires annual testing. A candidate who's fuzzy on what it does, or has never tested one, is telling you they haven't worked the compliance side of the trade, which is exactly the part that creates liability for your company months after the invoice is paid.

3. What license do you currently hold, and how long have you held it?

You want a direct, specific answer: journeyman or master, how long they've held it, and whether they can produce the number. A candidate who's vague, says they "think" it's still active, or can't answer quickly is worth verifying carefully with your state or local licensing board before you move forward. This is a case where you confirm it yourself rather than taking the answer at face value, the same way you'd verify a license for any regulated trade.

4. You're the only one on-site and the job turns out bigger than expected. How do you decide what to handle yourself versus call the office first?

Small shops don't have a foreman backing up every call, so this tests whether a plumber actually knows their own limits. A strong answer names a clear line: routine scope changes they'll just handle and quote, anything unusual, high-cost, or outside code they're confident on, they'll pause and call before proceeding. A candidate who says they'd just push through regardless, or who says they'd call for absolutely everything, is either overconfident or not ready to work independently yet.

5. Tell me about a time you had to explain an expensive or code-required repair to a customer who wasn't expecting it.

Listen for a real, specific story: what the issue was, how they explained it, whether they gave the customer options instead of just a number. A strong answer shows they walked the customer through why the repair or code requirement exists, not just that it exists, and let them decide without pressure. A candidate who can't produce an example, or whose story is really about talking someone into the pricier option, is a flag for a small shop where word of mouth is your whole marketing budget.

6. It's 11pm and a customer calls about water coming from the ceiling. How do you decide what's a true emergency versus something that can wait until morning?

Plumbing is one of the few trades where "emergency" gets used for everything, so this tests real judgment under pressure. A strong answer separates true emergencies (active flooding, no accessible water shutoff, sewage backup) from things that feel urgent but can be stabilized and scheduled (a slow drain, a running toilet), and explains how they'd walk a panicked customer through shutting off the water themselves if they can't get there right away. A candidate who treats every call as equally urgent, or who can't describe how they'd triage over the phone, will burn you out on after-hours calls that didn't need to happen tonight.

7. Tell me about a time a repair didn't go as planned and caused damage, water, drywall, whatever it was. What did you do?

Every experienced plumber has a story like this. Listen for whether they told the customer immediately and took responsibility, or tried to minimize it and hoped no one would notice. A strong answer includes what they did to stop the damage from getting worse and how they made it right. A candidate who can't produce an example, or who blames the house, the customer, or bad luck for something that was clearly their error, is telling you how they'll handle it the next time it happens on your account, not theirs.

8. How do you handle a general contractor who wants you to skip a permit or cut a corner to hit a deadline?

This comes up constantly for plumbers working new construction or remodels, and it's a direct test of whether code discipline survives pressure. A strong answer holds the line: explains why the shortcut won't pass inspection or creates a real risk, and offers whatever legitimate option exists to help the schedule instead. A candidate who says they'd "make it work" to keep the GC happy is telling you they'll sign off on something that comes back to your company's name, not theirs, when it fails an inspection or backs up a drain line six months later.

9. How do you keep your truck stocked so you're not making extra runs to the supply house?

Good plumbers treat their truck like their own small business. A strong answer describes an actual system: checking stock on a schedule, knowing which fittings, pipe sizes, and valves they use most, restocking after each job rather than waiting until they're empty on-site. A candidate who says they "just grab what's there" or has no system is telling you to expect wasted trips and delayed jobs.

10. Tell me about a time a customer or GC was frustrated with you or your work. What happened?

Every experienced plumber has this story. Listen for whether they stayed professional and focused on resolving the actual issue, or got defensive and let it escalate. A strong answer includes what they did to fix it and how the relationship ended up. A weak answer blames the other party entirely or brushes past the question, which usually means they haven't reflected on how their own reaction affects the outcome.

11. What's your attendance and reliability record like? Has anything ever come up that made you late or unavailable, and how did you handle it?

Ask this directly. A strong answer is honest about it happening occasionally, and specific about how they handled it: called ahead, gave real notice, coordinated coverage if needed. A candidate who claims a perfect record with no specifics, or gets defensive at the question, is harder to read. For a small shop with a handful of trucks, one no-show plumber can blow up a full day's schedule, and a customer who scheduled around a flooded basement remembers that you didn't show.

A scorecard you can score candidates against

Eleven questions only help if everyone interviewing is listening for the same thing, so score every candidate on the same signals instead of comparing gut feelings from separate conversations. Copy this into a doc and fill in a row per candidate.

How to screen plumber candidates without losing a week to it

Truffle is a candidate screening platform that combines resume screening, one-way video interviews, and talent assessments, so you can build a workflow around what actually matters for a licensed trade role like this one.

For a plumber, license verification has to come first, not somewhere in the middle of the process. And because this trade gets sourced through Indeed listings, walk-ins, and phone calls more than polished resumes (plenty of skilled plumbers can do excellent work and still not have a document that shows it), the workflow needs to fit how these candidates actually apply. This is the same dynamic you'll see if you also hire electricians or HVAC techs: verify the credential first, keep the resume optional, and lean on structured screening instead. If you're building out a broader trades roster, the same approach applies to automotive technicians too. Here's a workflow that fits a small plumbing business:

• Verify their journeyman or master plumber license is active with your state or local licensing board before you schedule anything. A quick check of the license number and status filters out applicants who aren't actually eligible to work unsupervised. Licensing rules vary by state and sometimes by municipality, so confirm against your own jurisdiction rather than assuming, and treat this the same way you'd verify a credential for any regulated role.
• Make the resume optional, not required. Plenty of your strongest candidates learned this trade through an apprenticeship, don't keep a LinkedIn profile current, and are more likely to call your office or walk in than fill out an online application. Where you do use resume screening, weight license status and work history over formatting or presentation, and don't screen someone out just because they didn't attach a document.
• A short one-way video interview before you commit an in-person slot. Ask 2-3 of the scenario questions above, like the emergency triage question or the GC pressure question, so you can see how someone actually thinks and communicates before you use up a working interview on them. A one-way video interview surfaces judgment and communication style, which are hard to read from a resume and much easier to hear on video.
• A mechanical ability assessment to check diagnostic reasoning before you're on-site together. A structured mechanical ability assessment on pressure, flow, and basic troubleshooting logic surfaces how someone reasons through a system, which is a harder signal to fake than a resume line about years of experience.
• A background check, run consistently and on a timeline you actually stick to. Background issues come up often enough in this trade that skipping the check to fill the seat faster is a false shortcut. Build it into the process so it doesn't stall out after you've already invested time in someone, on a role where you're sending that person into a customer's home alone.
• A working interview. Once someone's cleared license verification, video, assessment, and background check, bring them out on an actual job or two. This is where you confirm what the earlier steps only hinted at, including whether their safety and code habits hold up when you're not standing right next to them.

AI surfaces the evidence. You review it and make the call. It doesn't pick for you, and it never should for a hire where the wrong call carries safety and liability risk, not just a scheduling headache.

3 questions from the skills check we'd actually run for this role

A skills check only helps if it tests the reasoning the job needs, not trivia. These three are pulled from Truffle's mechanical ability assessment, the one we'd point you to for a trade where diagnosing pressure, flow, and fittings matters more than raw years. Try them yourself before you decide what "job-ready" means for your shop.

The point isn't these three questions. It's that a structured skills check like this surfaces how someone reasons through a system, which is a harder signal to fake than a resume line about years of experience. Truffle's AI scores and surfaces the results against the bar you set. You still make the call on who clears it.

Common hiring mistakes for this role

Requiring a resume or an online application when your best plumbers don't use either. A lot of strong candidates in this trade learned it through an apprenticeship, don't have a LinkedIn profile, and are more likely to call your office or walk in than fill out a formatted application online. Where these candidates do apply digitally, Indeed Resume is where this trade actually lives, not LinkedIn. Require a resume to even apply, and you filter out people who can do the work and keep the ones who are good at writing resumes instead.

Blaming "nobody wants to work" when the real issue is pay. If your pay is below what other shops in your area are offering, no amount of better screening fixes the turnover. Plumbers who take the job anyway tend to leave the moment something better comes along, and a revolving door gets chalked up to a labor shortage when the actual cause is the number on the offer.

Rushing or skipping the background check to fill the seat faster. It's tempting to move fast when you're short-staffed, but background check failures and unpredictable candidate history show up often enough in this trade that skipping the check, or not budgeting time for it to actually clear, is exactly what causes problems later, on a job where you're sending someone into a customer's home alone.

Writing a posting that blurs plumber with general handyman or maintenance work. A vague "maintenance tech, plumbing a plus" posting undersells the license requirement and the judgment this role requires, and pulls in applicants who aren't actually qualified to work on gas lines or backflow systems. Be specific about the license requirement and the safety responsibilities from the first line of the post.

Running a slow process and losing candidates to whoever calls back first. This is a tight labor market for licensed trades, and a strong plumber who doesn't hear from you within a day or two will take the next offer that comes in. Verify the license fast, screen fast, and don't let a good candidate sit in your inbox while you get around to it.