Commercial Plumber Interview Questions: What to Ask Potential Hires

What does a commercial plumber do?

Commercial plumbing service can look different from residential service, because of complex plumbing layouts in a variety of commercial settings, including businesses, hospitals, schools, hotels, and apartment complexes.

Commercial plumbers perform installations, repair, and maintenance on commercial plumbing and drainage systems. Employers seek candidates who display plumbing knowledge, problem-solving skills, attention to detail, and great customer service.

Online job search requirements typically include proper licenses and certifications, and a minimum two to five years of experience, depending on the position. Plumbing license requirements vary, as some states require plumbers to hold commercial licenses, while others offer master plumber or specialty licenses. 

General interview questions

1. Why do you want to work in plumbing?

2. Why do you want to work for our company?

3. What are your career goals?

4. Do you have a valid driver's license and clean driving record?

5. Can you give us a list of references?

General plumber job interview questions allow employers to discover applicants' backgrounds, including their goals, motivations, and how they approach challenges. Companies should formulate a hiring process to find the best candidates for the position.

At McWilliams & Son in Texas, a company that generated $12 million in annual sales in 2020, managers follow a layered hiring process to ensure new hires get placed in the right role.

“Interviews are always going to be with two different teams,” relates CFO Brad Pesek, who shared tips on a recent episode of ServiceTitan's “Toolbox for the Trades” podcast. “If they do well with the first team, they are passed on to a second round. Four people will have had a ‘touch’ on them before we consider hiring them.”

1. Why do you want to work in plumbing?

The classic "Tell me about yourself" question remains relevant, because hiring managers need to know why a plumbing candidate wants to work in commercial plumbing. It allows candidates to share why they have a passion for their work, their skill set, and how they want to continue their knowledge in the field.

2. Why do you want to work for our company?

This allows applicants to demonstrate their knowledge of your company and its core values. Find out what applicants know about the position, and what type of work they expect to perform.

Are they looking for a better work-life balance? What are their work schedule expectations? Are they willing to work off-hours for emergencies? Asking these questions puts their expectations, and yours, on the table for everyone to see.

This is also the time to ask about apprenticeship, on-the-job training, licenses, certifications, and work history, including how long they worked at previous jobs. You may also want to ask whether their current employer knows they're looking for a new job.

3. What are your career goals?

Do they simply want to earn more money than their last job, or are they interested in exploring a long-term career path? Either type of plumbing candidate may be a perfect fit for your company. Knowing what drives an employee and what they aim to accomplish shows their motivation and long-range planning. It can also help you determine if your company can provide opportunities to meet their career goals, which may result in a long-term employee.

4. Do you have a valid driver's license and clean driving record?

Your employees must drive to commercial properties in company trucks, so a valid driver's license and safe driving skills are of utmost importance—not only for the safety of your employees, but also for other motorists on the road. Plumbing job openings list this as a basic requirement.

5. Can you give us a list of references?

Hiring managers need to hear from others about how applicants performed at previous jobs, including information about their personality, interactions with co-workers, and how they tackled challenging plumbing projects.

Behavioral interview questions

1. Have you experienced a difficult interaction with a customer? How did you handle it?

2. How do you prevent mistakes on your projects?

3. Describe how you've worked as a team in a plumbing project.

4. Here's a plumbing scenario. How would you handle this?

The key to behavioral interview questions? Discovering the attitudes of your applicants to gain insight into how they approach problems and interact with others.

“We hire for attitude before we hire for aptitude,” says Angie Snow, Vice President of Western Heating & Air in Utah, who always asks one question to ascertain attitudes of candidates: “How’s your day going so far?”

She calls a simple question like that "experiential queries" to see how candidates respond. Their values shine through in their answers and the way they answer, says Snow, who also serves as Director of Customer & Product Training at ServiceTitan, and Success Coach at GoTime Success Group and Snow Business Coaching.

1. Have you experienced a difficult interaction with a customer? How did you handle it?

Asking about a difficult customer service experience gives candidates the chance to explain their overall philosophy on customer service, as well as what steps they take to provide an exceptional customer experience. Clear and timely communication with customers goes a long way toward customer relationship management (CRM).

2. How do you prevent mistakes on your projects?

Plumbing candidates can show they minimize mistakes by using a strong accountability process. Ask about what checks and balances they use to detect plumbing mistakes, and how to remedy them when they occur.

3. Describe how you've worked as a team in a plumbing project.

Gain understanding into how applicants approach teamwork, and how they communicate with co-workers and clients. Proper and efficient plumbing is essential to the safety and efficiency of buildings. Understanding building code requirements and achieving solutions to complex problems requires knowledge, problem-solving skills, excellent communication, and teamwork. If the role is managerial, they need to possess an effective management style. Your company's service to clients and the integrity of projects should remain of utmost importance to everyone on the team.

4. Here's a plumbing scenario. How would you handle this?

Asking applicants about an unknown job scenario that requires a specific skill set gives them the opportunity to demonstrate quick thinking and intuitive problem-solving skills. Their answers will indicate their thought processes and breadth of knowledge.

Technical knowledge interview questions

1. What was your most challenging project, and what did you learn from it?

2. What safety precautions do you take during plumbing projects?

3. What are the materials and tools you use most often? Do you have experience with specialized equipment?

4. What's the best way to resolve a clogged drain (or another plumbing issue)?

Plumbing companies seek commercial plumbers who can solve plumbing issues, whether minor or on a large scale, safely and efficiently. Asking questions with this in mind narrows your list of eligible candidates.

Gauge a candidate's knowledge of sustainable plumbing by asking about their knowledge of low-flow fixtures, hot water heater options other than conventional water heaters, or greywater systems, so you can provide the best plumbing options to your customers.

1. What was your most challenging project, and what did you learn from it?

Commercial plumbers know how to quickly fix leaky faucets or shower heads, but asking about challenging projects shows their level of mastery in the field. The process used to uncover solutions to plumbing challenges shows their level of critical thinking, which often dictates whether a project is successful. Employees who can quickly learn and adapt to new challenges strengthen projects and, in turn, your company.

2. What safety precautions do you take during plumbing projects?

Safety is key in the trades, and plumbing is no exception. Ask about their often-used procedures to ensure safety for themselves and those around them. Plumbers should wear personal protective equipment and know how to work safely in standing water or near hot equipment. Your company should reflect this priority by offering continuing training in key areas.

3. What are the materials and tools you use most often? Do you have experience with specialized equipment?

Detailed plumbing questions about types of pipe fittings and materials like PEX tubing or PVC pipes show what they know. Proper knowledge of tools like tubing cutters; pipe, seat, and basin wrenches; and reseating tools show they know how to use the right tools to get the job done. Ask about specialized equipment if it's part of the job skills you need.

4. What's the best way to resolve a clogged drain (or another plumbing issue)?

While customers may try to resolve clogs themselves, cup plungers, flange plungers and drain cleaners can only do so much. Plumbers should know how to efficiently use clog-eliminating tools like sink augers and closet augers to clear blockages to keep customers' sinks, showers, and toilets functioning properly.

Technology interview questions

1. How do you view mobile software in the plumbing industry?

2. What is your experience with using mobile technology in the industry?

3. What tools do you use to explain a problem and solutions to a customer?

Ask technology-related questions to see how much the candidate knows about plumbing trends and cloud-based software, such as ServiceTitan Commercial Service Software. A candidate's answer can help you determine if they see the value technology offers the plumbing industry.

1. How do you view mobile software in the plumbing industry?

If a candidate possesses experience with all-in-one plumbing software, they can explain how it increases efficiency and communication between the office and the field. With it, plumbers can provide branded job estimates right in the field, saving time and eliminating messy paper tickets. If your business also provides HVAC or electrical services, you can better coordinate large-scale projects, so they remain on time and on budget. 

2. What is your experience with using mobile technology in the industry?

Mobile technology allows commercial plumbers to see real-time schedules, materials and labor costs, and other critical job information. ServiceTitan Mobile streamlines communication from the field to the office, so nothing gets overlooked. 

3. What tools do you use to explain a problem and solutions to a customer?

Plumbers need to possess good communication skills, so they can clearly explain the problem and all possible solutions to customers. Presenting good-better-best options provides a low-pressure environment so customers can make the right decision. Customers may be more apt to choose the "best" option, understanding the upgrade will save money in the long term.

Payroll Interview Questions

1. What are your salary expectations?

2. Have you worked for a company that used performance-based pay?

3. What do you expect in terms of bonuses or SPIFs?

Online job postings show a current demand for commercial plumbers, from around 8,400, to 62,700 job openings, depending on the job search website and specific job title. Nationally, jobs in the plumbing occupation are forecast to rise by 4%, or 20,900 jobs, by 2029, according to the U.S. Bureau of Labor Statistics (BLS). Offering a competitive salary and benefits puts your company at the forefront for attracting and hiring top talent.

1. What are your salary expectations?

Nationally, plumbers, pipefitters, and steamfitters earn a median annual salary of $56,330, or $27.08 per hour, according to the BLS. Find out the salary range for your state and offer appealing benefits to attract the best job candidates, and reduce turnover rates.

2. Have you worked for a company that used performance-based pay?

If your plumbing company offers performance pay versus hourly rates, candidates need to understand how your commission and bonus structure affects the position. Using payroll software provides real-time timesheet tracking and automated bonuses, so you can tailor your pay structures to obtain the best results.

3. What do you expect in terms of bonuses or sales program incentive funds (SPIFs)?

Asking about bonuses or other incentives upfront allows you to share how your company values employee performance. These and other questions enable you to identify the best candidates and make the best hires for your company.