50 Plumbing Interview Questions to Find Top Plumbers

General plumbing interview questions

Ask these general questions first to get a better understanding of the candidate, their experience, and why they’re looking for a new job.

1. Tell me about yourself.

Starting the interview by asking a candidate to tell you about themselves reveals personality, communication skills, and professionalism. 

A strong answer is a brief, work-focused summary highlighting experience, work ethic, and career goals.

Watch out for long, unfocused answers, negativity about past employers, or no clear connection to plumbing work.

2. Describe your past experience as a plumber or in the plumbing trade.

Knowing a candidate’s plumbing experiences lets you know whether they are qualified enough to join your team.

A strong answer outlines their previous roles, the types of plumbing work they’ve handled, and the responsibilities they’ve taken on.

Vague descriptions, minimal hands-on experience, or inconsistent work history may signal a lack of experience. 

3. What skills or experience set you apart from other plumbing professionals?

Unique skills are good for your business, and a candidate with a diverse skill set or plenty of experience will help you take on more plumbing jobs with confidence.

A strong answer highlights distinct technical skills, specialized training, or customer service strengths that separate them from typical applicants.

Beware of candidates who provide generic answers, lack the ability to describe their strengths, or those who make unrealistic claims.

4. What do you enjoy most about being a plumber?

It’s important to enjoy your job, and people passionate about their work are more likely to help your business succeed. Asking what a candidate enjoys about being a plumber is a light-hearted way to see if that passion exists.

A strong answer conveys genuine enthusiasm for the trade, whether it’s solving problems, working with their hands, or helping customers.

If you find that your candidate answers this question with indifference or focuses mainly on money, they may not be passionate about their work.

5. What plumbing license do you have?

Credentials and licenses are a must in the plumbing industry, so it’s important to make sure your candidate is properly certified to do the job.

A strong answer clearly states a candidate’s current license level and confirms their credentials are up to date.

This question should be straightforward to answer—if they provide unclear licensing information, be sure to request to see their license.

JUMP TO: Role-specific interview questions

6. What do you know about our plumbing company?

If the candidate knows something about your company, it shows that they’ve done their research beyond reading the plumber job description and are proactive in learning about your business.

A strong answer demonstrates that the candidate researched your services and can explain why your business appeals to them.

If a candidate provides generic answers that can apply to any plumbing business, that’s a sign that they didn’t do any research. 

7. Why do you think you’re the right person for this job?

Asking a candidate why they are the right person for the job is a great way to make them envision success with your company while differentiating themselves from other candidates. It’s also a way to evaluate their confidence as a plumber.

A strong answer ties the candidate’s skills and experience directly to the needs of the role and shows confidence without arrogance.

If a candidate shows arrogance or an inability to explain why they are a good match, they may not be the right person for the job.

8. Do you have a valid driver’s license and a clean driving record?

Similar to questions about proper licensing, you want to ensure that your candidate is legally permitted and can be trusted to drive company vehicles.

A strong answer confirms that they hold a valid license, have a clean driving record, and understand the importance of safe driving on the job.

Watch out for candidates that say that they have a suspended license or multiple violations. Regardless, make sure to check every candidate’s license before hiring. 

9. Do you have experience using plumbing estimating software?

Likely not a deal breaker, but understanding a person’s experience with estimating software helps you get an idea for their workflow habits and their ability to operate the systems you use. 

A strong answer mentions the software they have used previously and expresses confidence in learning new systems quickly.

A lack of familiarity means more time spent onboarding. A candidate that shows resistance to using technology or unwillingness to learn new tools may be difficult to work with.

10. Can you provide two to three references?

References go a long way in building trust for a candidate. You want to make sure there are other experts who can vouch for your potential hire.

A strong answer readily provides multiple professional contacts who can speak credibly about their plumbing experience and work ethic.

If a candidate hesitates to give you professional references, their work history may be questionable. 

11. Do you have any questions for me?

Allowing the candidate to ask questions can also give you an idea about how serious they are about joining your team. 

A strong answer includes thoughtful questions about the company’s workflow, expectations, tools, or growth opportunities.

No questions isn’t always a bad thing, but when a candidate asks questions, it shows they are engaged and are trying to picture a situation where they can succeed with your business.

Background and experience interview questions

12. Can you describe your plumbing experience and the types of projects or systems you’ve worked on most frequently?

Understanding the types of plumbing projects a candidate has worked on helps you gauge whether their experience aligns with the work your business takes on. It also reveals how comfortable they are with different plumbing environments and systems.

A strong answer clearly outlines the kinds of jobs they’ve handled—such as residential installs, or specialized systems—and explains how often they worked on each.

If a candidate can’t describe their experience in detail, it may indicate that they have limited hands-on exposure or are exaggerating their skill level.

13. What formal training, certifications, or licenses do you hold, and how have they contributed to your development as a plumber?

Training, certifications, and licenses show that a candidate is committed to the trade and meets industry standards for safety and workmanship.

A strong answer names specific licenses or certifications and explains how each one has helped them improve their skills or advance in their career.

If a candidate can’t provide clear information about their credentials—or seems unsure of what their training involves—they may have outdated qualifications or a lack of required certifications.

14. Tell me about a particularly challenging plumbing job you’ve completed. What made it difficult, and how did you approach it?

Hearing about difficult jobs helps you understand how the candidate problem-solves, manages pressure, and applies their technical knowledge.

A strong answer describes a specific challenge, walks you through their approach to diagnosing and fixing the issue, and highlights the successful outcome.

If a candidate can’t recall a meaningful example or only blames others for the difficulty, it may indicate poor accountability or limited real-world experience.

15. How have your responsibilities evolved throughout your plumbing career?

Learning how a candidate’s responsibilities have grown over time shows whether they’ve demonstrated initiative, reliability, and progression in their trade.

A strong answer explains how they took on more autonomy, more complex tasks, or leadership duties as they advanced in their career.

If a candidate’s responsibilities haven’t changed over several years, it may suggest a lack of growth or readiness for higher-level work.

16. What experience do you have working with specialized systems (e.g., commercial boilers, medical gas, hydronic heating, or high-rise plumbing)?

Specialized systems require advanced skills, additional training, and strong attention to detail, so it’s important to know whether a candidate can handle these types of jobs.

A strong answer clearly identifies the specialized systems they’ve worked with and briefly explains their responsibilities or relevant certifications.

If a candidate gives vague details or avoids specifics, they may not actually have the specialized experience they claim.

Technical plumbing interview questions

Technical or operational interview questions help you ensure the candidate has the specific skills and knowledge they need to fix common plumbing issues.

These questions go beyond determining whether a candidate would fit in with your team and instead focus on their ability to perform the work up to your expectations.

17. What plumbing tools do you always bring with you to the job site for plumbing repairs or installations?

Asking a candidate’s preferred plumbing tools helps you understand whether the candidate is prepared, organized, and familiar with the essential tools required for common plumbing tasks.

A strong answer lists core tools—such as pipe wrenches, basin wrenches, drain snakes, tubing cutters, pliers, and inspection equipment—and explains why they rely on them.

If a candidate cannot name basic tools or gives an overly generic list, it may indicate inexperience or poor preparation habits.

18. What chemical drain cleaners would you recommend to clear a clogged drain?

This question reveals whether the candidate understands safe and appropriate product usage, especially when working in customers’ homes.

A strong answer discusses when chemical cleaners are appropriate and emphasizes safety or environmental considerations.

If a candidate immediately suggests harsh chemicals without mentioning the importance of pipe material or safety, it may signal poor judgment.

19. Should you install steel plumbing under a sink? Why or why not?

This question assesses the candidate’s understanding of proper material use and potential corrosion issues.

A strong answer explains that steel pipes are generally not recommended because they corrode easily, which can lead to leaks or contamination.

If a candidate indicates they would use steel without acknowledging corrosion risks, it may show a lack of basic material knowledge.

20. How do you snake clogged pipes?

Pipe snaking is a common service task, so the candidate should know how to do it safely and effectively.

A strong answer describes selecting the right snake, feeding it carefully into the pipe, working the blockage slowly, and testing the system afterward.

If a candidate can’t explain the process clearly, they might have insufficient hands-on experience with routine plumbing jobs.

21. Do you prefer PVC or copper pipes? Why?

This question helps you understand the candidate’s reasoning skills and familiarity with pipe materials, codes, and job requirements.

A strong answer compares the two materials and explains that preference depends on the application—such as cost, durability, water quality, or local code.

If a candidate claims one material is always better without context, it may suggest a lack of flexibility or incomplete knowledge.

22. What causes a sump pump to fail?

Understanding common sump pump failures is key for both troubleshooting and preventive maintenance.

A strong answer mentions causes such as power failure, switch problems, clogged discharge lines, improper installation, or old age.

If a candidate cannot explain common failure points, it may signal limited experience with residential drainage systems.

23. Have you ever installed an air conditioning unit? Walk me through the steps you took.

This question helps you assess whether a candidate has crossover skills that may be useful for HVAC-integrated plumbing systems.

A strong answer provides a concise, step-by-step overview that includes safety checks, mounting, drainage setup, and testing.

If a candidate claims experience but can’t describe the steps clearly, they may have overstated their abilities.

Behavioral interview questions for plumbers

Asking behavioral questions will help you better understand how your plumbing candidate will act in certain situations. 

Make sure the questions are relevant to the types of scenarios they’ll face on the job.

24. Tell me about a time when you offered excellent customer service as a plumber.

There are few things more important for your plumbing business than good customer service, so this question will give you an idea of how your candidate is able to satisfy the customers with each job.

A strong answer describes the situation clearly, explains the steps they took to resolve the issue, and shows that they remained calm and professional throughout.

Watch out if a candidate blames the customer or can’t explain how they resolved the situation—they may have poor customer service skills.

25. What was the hardest plumbing job you’ve ever had to tackle? How did you overcome it?

This question ties back to experience and learning about a candidate’s abilities in difficult situations. This answer could focus on a particular skill set or creative problem-solving solving your business is looking for.

A strong answer describes how the candidate tracked tasks, communicated with team members, and ensured the job stayed on schedule.

If a candidate cannot provide an example or suggests they “just wing it,” they may have weak organizational habits.

26. Tell me about a time you had to work for a difficult customer. How did you make a good impression?

It’s important to know if your plumbing candidate can manage the ups and downs of difficult customers and not put your business at risk of losing work. 

A strong answer explains how they stayed calm, listened to the customer’s concerns, and took practical steps to resolve the issue professionally.

If a candidate becomes defensive, blames the customer, or cannot describe how they turned the situation around, it may indicate weak customer-service skills.

27. Have you ever had to work in a team? What was your role?

Teamwork is an important aspect of any company, so you want to be sure your candidate can work with people to complete jobs and make the business run more efficiently.

A strong answer clearly describes the team’s objective, their specific role, and how they contributed to completing the job successfully.

If a candidate says they prefer not to work with others or minimizes the importance of teamwork, they could create friction on the job.

28. How do you organize your day when you have multiple plumbing service calls?

Understanding how a candidate constructs and manages an active and sometimes overwhelming schedule is a great way to evaluate if they can handle being a part of a growing business.

A strong answer describes how they prioritize urgent calls, plan routes, prepare tools in advance, and communicate clearly with customers and the office. Bonus points if they mention any plumber apps that they use.

If a candidate cannot explain a structured approach to managing multiple calls, it may indicate they struggle with organization or time management.

Compensation-based questions

Hiring the perfect candidate for your growing plumbing company means finding the right experience at the right price. To make sure you’ll meet their wage expectations, ask one of the following questions.

29. What are your salary expectations for this position?

Asking about salary expectations helps you understand whether the candidate’s expectations are aligned with your budget and whether they understand the value of their own experience. 

A strong answer provides a clear, reasonable number based on their experience, market rates, and the responsibilities of the role.

Salary expectations that are too low can suggest a lack of confidence or limited experience, while expectations that are too high may indicate unrealistic self-assessment.

30. What salary range are you looking for?

A salary range creates a more relaxed environment to have a negotiation. It helps you understand whether it’s even possible to work with a candidate while giving the candidate the opportunity to showcase their qualifications in order to justify their range.

A strong answer offers a balanced range backed up by their skills, certifications, and years of experience.

If a candidate provides a very wide or very vague range, it may indicate uncertainty about their own value or potential difficulty during compensation discussions.

Pro Tip: Have a firm salary range in mind before you start your interview process so you’re ready to answer any pay-related questions your candidates may have. As a guide, plumbers in the United States earn, on average, $62,970 annually, or $30.27 per hour.

READ MORE: Plumbing Industry Statistics and Trends to Know for 2025 (and Beyond)

Role-specific plumbing interview questions

Depending on the type of plumber you’re looking to hire, you’ll want to ask questions specific to their skill level and experience. 

This helps you identify where a person fits into your plumbing business and how much you can expect to pay them for their experience and expertise.

Plumbing apprentice interview questions

31. Why do you want to work in the plumbing industry?

This question helps you understand the candidate’s motivation and whether they’re committed to developing a long-term career in the trade. Passion and genuine interest often translate into stronger performance, better customer service, and a willingness to continue learning.

A strong answer clearly explains what draws them to plumbing—such as problem-solving, hands-on work, or the satisfaction of helping customers.

If a candidate can’t explain why they want to be in the industry, it may indicate a lack of long-term commitment or genuine interest.

32. When will you be eligible to take your journeyperson plumbing exam? 

Plumbing licensing timelines often affect the work a candidate can legally do. If your state requires plumbers to take an exam to be qualified, this question helps you confirm whether the candidate is progressing appropriately through training requirements.

A strong answer gives a clear timeframe based on their hours completed, coursework, or state-specific requirements.

If a candidate doesn’t know when they’ll be eligible or shows little awareness of the licensing process, it may indicate poor planning or lack of commitment to advancing in the trade.

Plumbing journeyperson interview questions

33. How long have you been a journeyperson plumber?

This question helps you determine the candidate’s level of hands-on experience and how long they’ve been working independently in the trade. Time spent as a journeyperson often reflects their exposure to complex jobs and ability to work without direct supervision.

A strong answer clearly states their years of experience and may highlight the type of work they’ve done during that time.

If a candidate is unclear about their timeline or seems to exaggerate their experience, it may be a sign that their background needs closer verification.

34. Where do you see yourself in five years as a journeyperson plumber?

This question reveals a candidate’s long-term goals and whether they envision growing with your company—this can translate to more motivation, initiative, and commitment.

A strong answer explains career aspirations, such as taking on leadership responsibilities.

If a candidate shows no vision for their future or seems indifferent about their career path, they might lack ambition or long-term fit.

Master plumber interview questions

35. How do you stay up to date with changes and trends in the plumbing industry?

The plumbing industry changes frequently, with new codes, tools, and technologies. It’s important to know whether the candidate takes the initiative to keep their skills current, which is essential for safety, efficiency, and compliance. 

A strong answer mentions methods such as attending workshops, taking courses, reading trade publications, or participating in professional organizations.

If a candidate shows little interest in ongoing learning, they may be resistant to change or may fall behind on industry standards.

36. Have you ever trained an apprentice? Tell me about the experience.

Training others requires patience, communication, and confidence in one’s own abilities. Asking this question helps you evaluate the candidate’s leadership skills and ability to mentor developing plumbers.

A strong answer describes how a candidate guided an apprentice, what responsibilities they took on, and the positive outcomes of the experience.

Beware of master plumbers who can’t explain how they communicated or supported the apprentice—it may indicate poor leadership or an inability to collaborate.

37. What are your plumbing career goals?

Understanding a candidate’s aspirations helps you plan for long-term growth or leadership needs.

A strong answer describes clear, realistic goals such as becoming a master plumber, specializing in a niche area, or moving into supervisory roles.

If a candidate cannot describe any goals or expresses aspirations that don’t align with the role, they might be a poor long-term fit.

Commercial plumbing interview questions

38. Have you ever plumbed an office building?

Office buildings often require plumbers with advanced system knowledge, coordination with other trades, and strict compliance with codes.

A strong answer describes the type of office building a candidate has worked on, the systems they worked on, and their role in completing the project.

If a candidate cannot give specifics or speaks only in general terms, it may indicate limited commercial experience.

39. Have you ever had to install a plumbing system for an entire floor of a building? How did you start?

This question reveals the candidate’s ability to handle large-scale installations and their approach to planning and sequencing the work..

A strong answer explains how they reviewed the plans, identified key fixtures and pipe routes, and coordinated their work with other trades to ensure a smooth installation.

If a candidate cannot describe a clear process or talks only about small tasks, it may signal they lack experience with full-floor or large commercial installations.

40. Tell me about a time when you had to review blueprints or building codes to complete a job. What did you look for?

Commercial projects rely heavily on accurate blueprint reading and adherence to codes. This question helps you assess whether the candidate is comfortable working with technical documents and understands compliance requirements. 

A strong answer describes how they checked fixture locations, pipe sizing, venting requirements, and code compliance before beginning the work.

If a candidate cannot explain what they look for in blueprints or code, it may indicate weak technical knowledge or potential errors on the job.

Residential plumber interview questions

41. What’s the first step you should take to fix a clogged pipe?

This question helps you understand whether the candidate knows how to approach common residential problems systematically and safely. 

A strong answer explains that they begin by assessing the blockage—such as checking accessible traps or inspecting for obvious obstructions—before choosing the appropriate tool or method.

If a candidate jumps immediately to aggressive measures like chemicals or snaking without assessing the situation, it may indicate poor troubleshooting skills.

42. Tell me about your experience installing water-based heating systems.

This question helps you confirm whether the candidate has the specialized skills needed for hydronic heating, which requires precision and a solid understanding of plumbing and heating components.

A strong answer describes the types of systems they’ve installed, their responsibilities, and how they ensured proper setup and testing.

If a candidate cannot provide details or confuses water-based heating with unrelated systems, it may indicate limited or no experience in this area.

43. What expert advice would you give a homeowner dealing with a leaking pipe or fixture?

This question helps you gauge the candidate’s communication skills and ability to educate customers—an important part of residential plumbing. 

A strong answer mentions advising homeowners to shut off the water, contain the leak, avoid temporary fixes that could worsen the problem, and call a professional promptly.

If a candidate gives advice that is unsafe, overly technical, or dismissive of the homeowner’s concerns, it may indicate poor customer service skills.

Hospital plumbing technical questions

44. What technical experience do you have with plumbing hospitals?

This question helps you understand whether the candidate has worked in highly regulated environments where plumbing systems impact patient safety. 

A strong answer describes specific hospital systems they’ve worked on—such as medical gas, sterilization equipment, or specialized drainage—and explains their role in maintaining or installing them.

Beware of candidates who can’t describe hospital-specific systems or only reference general plumbing work; it may indicate they lack the required experience for medical facilities.

45. Have you ever installed medical gas or oxygen in hospitals? Walk me through how you did it.

Medical gas work demands strict adherence to codes and careful documentation, and it’s important to have plumbers who know how to deal with this.

A strong answer explains the steps clearly, including verifying plans, shutting down or isolating systems safely, installing and testing lines, inspections, and more.

If a candidate cannot walk through the process or seems unaware of certification requirements, they may not be qualified for medical gas installations.

46. Describe how you would install or repair medical gas and waste disposal systems.

This question helps you assess the candidate’s understanding of both installation and maintenance for hospital-specific systems that must operate flawlessly. 

A strong answer outlines steps such as following NFPA or local medical gas codes, ensuring proper material handling, performing leak and pressure tests, and documenting the work thoroughly.

Beware of vague or overly simplistic descriptions. That may indicate they lack the technical depth needed for hospital plumbing systems.

Plumbing engineer interview questions

47. Walk me through your process for designing a plumbing system for a new commercial building.

This question helps you understand how the candidate approaches complex design projects from concept to completion. 

A strong answer describes evaluating building occupancy, water supply demands, drainage needs, pipe sizing, code constraints, and coordination with architects and other trades before drafting the design.

If a candidate cannot outline a clear or logical design process, it may indicate a lack of experience with commercial-scale engineering work.

48.  What methods or software tools do you use for plumbing system modeling?

Asking about engineering software tools allows you to assess the candidate’s technical proficiency and comfort with modern design tools used in engineering environments.

A strong answer refers to tools like Revit, AutoCAD, or BIM platforms and explains how they help streamline design, prevent clashes, and ensure precise layouts.

If a candidate lacks experience with essential modeling tools, it may slow collaboration and reduce design efficiency on commercial projects.

Plumbing supervisor interview questions

49. How do you manage, assign, and prioritize daily workloads for your plumbing team?

This question helps you understand the candidate’s ability to lead a team, make quick decisions, and keep work flowing efficiently. 

A strong answer explains how they assess job priority, match tasks with the right team members, communicate clearly, and adjust the plan when emergencies or schedule changes occur.

If a candidate cannot describe a structured approach to delegation and prioritization, it may indicate difficulty managing a fast-paced workload.

50. What steps do you take to ensure the quality of work performed by your crew, particularly on large or high-risk plumbing projects?

Quality control is critical for preventing failures, rework, and costly delays. This question helps you evaluate the candidate’s commitment to safety, consistency, and high workmanship standards. 

A strong answer mentions steps like performing regular inspections, reviewing work against plans, enforcing standards, providing feedback, and verifying final testing or sign-offs.

If a candidate shows little focus on quality assurance or relies solely on workers to catch their own mistakes, it may lead to poor project outcomes.

Hiring the right plumber starts with asking the right questions. By combining technical, behavioral, and role-specific interview questions, you can better understand a candidate’s skills, work ethic, and long-term potential with your company.