Question 1

Walk me through how you'd rough in a bathroom with a toilet, a vanity and a tub on a second floor.

Accepted Answer

This is the everyday job for a journeyman on new construction or remodels. They want to hear an order of work and code awareness without prompting. Start with checking the plans and fixture locations against the framing, and where the joists run Explain how you'd size and route the drain, keeping trap arm lengths within code for the pipe size Name how each fixture gets vented, and where you'd tie into the stack Mention nail plates, blocking for the valve and supports for the pipe Close with the test you'd put on it before the inspector shows up

Question 2

How do you test a drain and vent system before rough-in inspection?

Accepted Answer

A failed inspection costs the shop a return trip and annoys the builder. They want to know your routine, not a textbook answer. Describe the test your area's inspector expects, such as a water test or an air test Talk about capping or plugging openings with test balls and caps Explain how you'd walk the system looking for weeps before calling for inspection Say what you do when the gauge drops and you can't see the leak

Question 3

Tell me about a callback you caused. What happened and what did you change afterward?

Accepted Answer

Everyone has callbacks. They're checking whether you own them and whether you learned something concrete. Pick a real one, like a compression fitting that wept or a slip joint under a sink Say plainly what you did wrong Explain how you made it right with the customer Name the habit you added, such as running water longer before leaving or checking every joint with a paper towel

Question 4

A customer says their water heater is making popping noises and they have no hot water upstairs. How do you work it?

Accepted Answer

Service shops want to see how you diagnose before you sell. Water heaters are a big share of service calls. Start by checking whether it's gas or electric, its age from the label, and the venting Explain that popping often points to sediment and what you'd check for the no-heat side Mention checking the relief valve and whether there's an expansion tank on a closed system Talk about giving the customer repair and replace options honestly

Question 5

How do you size a gas line for a new range added to an existing house?

Accepted Answer

Gas work carries real risk, and they need to know you can do it by the book in states where a journeyman is allowed to. Say you'd total the connected load from the appliance ratings Explain measuring the longest run from the meter and using the sizing table in the adopted code Mention checking the existing trunk can carry the added load Close with the pressure test and leak check before lighting anything

Question 6

You're running a main line with a camera and see roots and a belly in the pipe. What do you tell the homeowner?

Accepted Answer

Sewer calls are where trust gets won or lost. They want honest diagnosis and clear options. Explain you'd mark the location and depth with a locator Show the footage to the homeowner and explain what a belly means for future clogs Lay out options from clearing and rechecking, to a spot repair, to replacement Say you'd be clear about which option actually fixes the problem

Question 7

Which code book does our area use, and how do you look things up on a job?

Accepted Answer

A journeyman works without someone checking over their shoulder. They want to know you use the book, not memory alone. Name the code adopted in the area, whether the International Plumbing Code or the Uniform Plumbing Code, plus any local amendments you know of Explain how you keep your book tabbed or use the digital version on your phone Give a real example of something you looked up on a job

Question 8

Have you worked with a backflow preventer, and when is one required?

Accepted Answer

Cross-connection control comes up on irrigation, boilers and commercial work. Shops that do testing want to know if you're certified or willing to be. Name the devices you've installed, such as a reduced pressure zone assembly or a double check valve Explain the basic idea of matching the device to the hazard Say whether you hold a tester certification or want to get one Mention that the local water authority often sets its own rules

Question 9

How have you trained or supervised an apprentice?

Accepted Answer

Journeymen usually ride with an apprentice. The shop's future plumbers learn from you. Describe letting them do the work while you watch, instead of doing it for them Give an example of catching a mistake before it went in the wall Mention how you handle an apprentice who's late or careless

Question 10

A general contractor wants you to move a drain that's already been inspected, and the builder is pushing you to skip the reinspection. What do you do?

Accepted Answer

They're testing whether you'll protect the shop's license under pressure from a customer. Say the change needs to be tested and inspected, no matter who asks Explain you'd bring in your supervisor or the master who pulled the permit Offer ways to keep the schedule moving, like calling for a quick reinspection

Question 11

How do you handle a customer who's upset about the price after you've quoted a job?

Accepted Answer

Service shops using flat-rate pricing need techs who can explain a price calmly without discounting on the spot. Explain the price in terms of what's included and the warranty Offer options at different levels where they exist Say you don't argue, and you're fine leaving if they decline

Question 12

Why are you looking to leave your current shop?

Accepted Answer

Plumbing shops lose people to each other all the time. They want to know if you'll stay. Give a real reason, like wanting more service work or a shorter drive Keep it about what you want next, not what's wrong with your boss Tie it to something this shop actually offers

Journeyman Plumber interview questions, and how to answer them

The 8 questions you will almost certainly get

A forgettable answer, and a better one

"Walk me through how you'd rough in a bathroom with a toilet, a vanity and a tub on a second floor."

"How do you test a drain and vent system before rough-in inspection?"

Questions to ask them

Need more Journeyman Plumber interviews to prep for?

The question	What they want to know	Your angle
Walk me through how you'd rough in a bathroom with a toilet, a vanity and a tub on a second floor.	This is the everyday job for a journeyman on new construction or remodels. They want to hear an order of work and code awareness without prompting.	Start with checking the plans and fixture locations against the framing, and where the joists run
How do you test a drain and vent system before rough-in inspection?	A failed inspection costs the shop a return trip and annoys the builder. They want to know your routine, not a textbook answer.	Describe the test your area's inspector expects, such as a water test or an air test
Tell me about a callback you caused. What happened and what did you change afterward?	Everyone has callbacks. They're checking whether you own them and whether you learned something concrete.	Pick a real one, like a compression fitting that wept or a slip joint under a sink
A customer says their water heater is making popping noises and they have no hot water upstairs. How do you work it?	Service shops want to see how you diagnose before you sell. Water heaters are a big share of service calls.	Start by checking whether it's gas or electric, its age from the label, and the venting
How do you size a gas line for a new range added to an existing house?	Gas work carries real risk, and they need to know you can do it by the book in states where a journeyman is allowed to.	Say you'd total the connected load from the appliance ratings
You're running a main line with a camera and see roots and a belly in the pipe. What do you tell the homeowner?	Sewer calls are where trust gets won or lost. They want honest diagnosis and clear options.	Explain you'd mark the location and depth with a locator
Which code book does our area use, and how do you look things up on a job?	A journeyman works without someone checking over their shoulder. They want to know you use the book, not memory alone.	Name the code adopted in the area, whether the International Plumbing Code or the Uniform Plumbing Code, plus any local amendments you know of
Have you worked with a backflow preventer, and when is one required?	Cross-connection control comes up on irrigation, boilers and commercial work. Shops that do testing want to know if you're certified or willing to be.	Name the devices you've installed, such as a reduced pressure zone assembly or a double check valve