21 Plumbing Maintenance & Repair Practice Questions & Answers

Every Plumbing Maintenance & Repair practice question from the CAMT Apartment Maintenance Practice Test, with the correct answer and a short explanation.

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1. A fixture's drain vent connects to the drain line downstream of the trap. What is the vent's MAIN function?
- A.Carry roof rainwater down into the building's waste stack
- B.Admit air so draining flow cannot siphon the trap seal✓ Answer
- C.Speed waste flow by adding pressure inside the drain line
- D.Filter sewer gas before it reaches the fixture drain opening
A vent equalizes air pressure in the drainage system. Without it, water rushing down the drain pulls a vacuum behind it and siphons the water out of the trap, leaving an open path for sewer gas. Vents move air, not water, and they do not filter anything.
Source: NAAEI CAMT curriculum, Plumbing Maintenance and Repair — drain ventingReport a problem with this question
2. A resident reports a sewer smell near the tub in a guest bathroom that is almost never used. The tub drains normally. What is the MOST likely cause?
- A.The tub spout diverter is worn and no longer seats fully
- B.The water heater setting is too low for that end of the unit
- C.The trap seal has evaporated because the tub is seldom used✓ Answer
- D.The tub's overflow gasket has hardened and is leaking water
Every fixture trap holds a plug of water that blocks sewer gas. In a fixture that goes unused for weeks, that water evaporates and the trap dries out. Running water at the fixture for a minute restores the seal, and scheduling periodic flushing of unused fixtures prevents it.
Source: NAAEI CAMT curriculum, Plumbing Maintenance and Repair — trap seals and sewer gasReport a problem with this question
3. A kitchen sink drains slowly, and a nearby fixture gurgles each time it drains. What does this pattern MOST likely indicate?
- A.A failed strainer gasket seated under the sink basket flange
- B.A restricted vent or a partial blockage in the shared branch✓ Answer
- C.Water pressure at the building main has risen above normal
- D.A worn faucet cartridge letting hot water cross into the cold
Gurgling is air being pulled through a trap seal because the drain cannot get air the normal way. Slow flow plus gurgling at a second fixture points at the shared branch or its vent, not at the individual fixture, so the technician should look downstream rather than at the strainer.
Source: NAAEI CAMT curriculum, Plumbing Maintenance and Repair — drainage and venting symptomsReport a problem with this question
4. A resident reports that water rises in the tub whenever the toilet is flushed. Which system does this complaint belong to, and why?
- A.The waste exit system, because flow cannot leave past a blockage✓ Answer
- B.The roof vent only, because the vent opening has been capped shut
- C.The water distribution system, because hot and cold have crossed
- D.The water supply system, because incoming pressure is too high
Apartment plumbing is taught as water supply, water distribution, and waste exit. Water appearing at a lower fixture when another discharges is drainage backing up past an obstruction, so it belongs to the waste exit side. Supply-side faults show as pressure or temperature complaints instead.
Source: NAAEI CAMT curriculum, Plumbing Maintenance and Repair — the three apartment plumbing systemsReport a problem with this question
5. Water is spraying from a supply line under a kitchen sink while the resident stands by. What should the technician do FIRST?
- A.Set towels and a bucket to contain the spreading water
- B.Photograph the damage for the service request record
- C.Shut the building main to isolate the entire riser
- D.Close the angle stop under the sink to stop the flow✓ Answer
Stop the water at the closest point of control first, then work outward only if that fails. The angle stop isolates the one fixture in seconds without cutting service to other apartments, and everything else — containment, documentation, repair — is done after the flow stops.
Source: NAAEI CAMT curriculum, Plumbing Maintenance and Repair — emergency water shutoff hierarchyReport a problem with this question
6. The angle stop under a leaking toilet is corroded and will not close all the way. What should the technician do NEXT?
- A.Ask the water utility to shut the street service off
- B.Force the stop shut with pliers until it seats fully
- C.Close the unit or branch valve that serves the apartment✓ Answer
- D.Cap the riser line at the toilet's fill valve inlet
Shutoff control escalates one level at a time: fixture stop, then unit or branch valve, then riser or building main. Forcing a corroded compression stop snaps the stem or the pipe and turns a small leak into a flood, so the failed stop is replaced after the branch is isolated.
Source: NAAEI CAMT curriculum, Plumbing Maintenance and Repair — angle stops and unit shutoff valvesReport a problem with this question
7. A toilet refills by itself for a few seconds every several minutes although no one is using it. What is the MOST likely cause?
- A.Condensation forming on the outside of the cold porcelain tank
- B.A partly closed angle stop that restricts how fast the tank fills
- C.A refill tube that discharges into the top of the overflow
- D.A worn flapper letting tank water seep down into the bowl✓ Answer
Intermittent refill with no use means water is leaving the tank silently, and the flapper or its seat is the usual path. A dye tablet in the tank that shows up in the bowl confirms it. A refill tube aimed into the overflow is correct practice, and condensation is not a leak.
Source: NAAEI CAMT curriculum, Plumbing Maintenance and Repair — toilet fill and flush valve diagnosisReport a problem with this question
8. Water keeps appearing on the floor around a toilet that rocks slightly when it is used. What is the correct repair?
- A.Run a bead of sealant around the base to stop the seepage
- B.Reset the bowl on a new wax seal and secure the closet bolts✓ Answer
- C.Replace the fill valve and raise the tank's water level
- D.Tighten the closet bolts down until the rocking stops
A rocking bowl works the wax seal loose so waste water escapes at the flange on every flush. The bowl must be lifted, the old wax scraped off, and a new seal installed, because wax is never reused. Overtightening the bolts to stop the rock cracks the porcelain instead of sealing it.
Source: NAAEI CAMT curriculum, Plumbing Maintenance and Repair — toilet flange, wax ring and closet boltsReport a problem with this question
9. A toilet flushes weakly, yet the tank fills to its marked line and no other fixture in the unit is affected. What should be checked FIRST?
- A.The rim jets and siphon jet for mineral blockage✓ Answer
- B.The closet flange for corrosion below floor level
- C.The building's water pressure at the main riser
- D.The wax ring beneath the bowl for a failed seal
A toilet flushes by siphon action, which needs the tank's water delivered fast through the rim and jet openings. Scale narrows those passages and the bowl only dribbles. A supply problem would affect other fixtures, and a wax or flange fault shows as floor water, not weak flush.
Source: NAAEI CAMT curriculum, Plumbing Maintenance and Repair — toilet flush diagnosisReport a problem with this question
10. A single-handle faucet whose handle rotates a slotted metal ball over rubber seats and springs is which type of faucet?
- A.Compression
- B.Ceramic disc
- C.Ball✓ Answer
- D.Cartridge
The four faucet families are ball, cartridge, ceramic disc, and compression. Only the ball design uses a slotted ball turning against spring-loaded rubber seats, and those seats and springs are the parts usually replaced when it drips. Compression faucets have two handles and washers.
Source: NAAEI CAMT curriculum, Plumbing Maintenance and Repair — faucet typesReport a problem with this question
11. A resident reports weak flow at one bathroom faucet only; every other fixture in the apartment is normal. What is the MOST likely cause?
- A.Sediment built up in the bottom of the water heater
- B.An undersized supply riser serving that apartment
- C.A failed pressure regulator on the building main
- D.A clogged aerator or a partly closed angle stop✓ Answer
Symptoms tell you where to look: a problem at one outlet only lives between that fixture's stop and its spout. Debris caught in the aerator screen and a stop that was never reopened fully are the two common causes. A main, regulator, or heater fault would slow several fixtures at once.
Source: NAAEI CAMT curriculum, Plumbing Maintenance and Repair — fixture supply line, angle stop and aeratorReport a problem with this question
12. A flange plunger has not cleared an object blocking a toilet. Which tool is the appropriate NEXT choice?
- A.A powered drum machine run down the roof vent
- B.A closet auger worked through the bowl trapway✓ Answer
- C.A chemical drain opener poured into the bowl
- D.A garden hose forced into the bowl's outlet
A closet auger has a protective sleeve and a bent tip made to follow the bowl's trapway without scratching the porcelain, and it is hand cranked, which keeps it within the maintenance technician's tool set. Chemicals are never used in a toilet and a hose creates a cross-connection.
Source: NAAEI CAMT curriculum, Plumbing Maintenance and Repair — plunger and closet auger useReport a problem with this question
13. Why should a technician avoid clearing a slow apartment drain with a chemical drain opener?
- A.It is effective on hair but never on kitchen grease
- B.It works only after all standing water has been drained
- C.It can injure the next worker and damage older piping✓ Answer
- D.It voids the property's warranty on the sink faucet
Caustic product that does not clear the line sits in the trap, so the next person who opens that joint gets splashed with it, and the heat and chemistry attack seals, traps, and older pipe. Mechanical clearing with a plunger or hand auger removes the blockage instead of masking it.
Source: NAAEI CAMT curriculum, Plumbing Maintenance and Repair — clearing drains without chemical drain openersReport a problem with this question
14. A first-floor tub backs up every time the apartment above it drains. What does this MOST likely indicate?
- A.A failed pop-up stopper seal in the upper unit's tub
- B.A vent stack sized too large for the building's height
- C.A blockage in the shared drain line below both units✓ Answer
- D.A dry trap in the first-floor tub that needs refilling
When discharge from one unit surfaces at a lower fixture, the obstruction is downstream of both, in the shared branch or main, not in either fixture trap. That is past the point a hand auger at the tub can reach, so the technician reports it and it goes to a licensed plumber or drain contractor.
Source: NAAEI CAMT curriculum, Plumbing Maintenance and Repair — main line versus fixture blockageReport a problem with this question
15. A storage water heater's temperature and pressure relief valve is dripping steadily. What is the correct response?
- A.Find out why it is relieving and correct that condition✓ Answer
- B.Add a shutoff valve in the discharge line as a stopgap
- C.Cap the discharge pipe until a replacement valve arrives
- D.Plug the valve outlet and raise the thermostat setting
That valve is the tank's last protection against rupture from excess temperature or pressure, so its outlet must stay open to atmosphere with no cap, plug, or valve in the discharge line. A drip is a symptom — excessive setting, thermal expansion, or a fouled seat — and the cause is what gets fixed.
Source: Model plumbing code general principle — temperature and pressure relief valve dischargeReport a problem with this question
16. An electric storage water heater has just been installed and its piping connected. What must happen BEFORE power is restored to it?
- A.The drain valve must be opened to purge the elements
- B.The relief valve must be lifted and left partly open
- C.The thermostat must be set to its highest position
- D.The tank must be completely filled with water✓ Answer
An immersion element is cooled by the water surrounding it. Energized in an empty or partly filled tank it dry-fires and burns out almost immediately, so the tank is filled and air purged through an open hot faucet before power is turned on and the setting is checked.
Source: NAAEI CAMT curriculum, Plumbing Maintenance and Repair — water heater replacement and start-upReport a problem with this question
17. A storage water heater rumbles and pops during a heating cycle. What is the MOST likely cause and the correct preventive action?
- A.A failed dip tube; drain the tank and replace the anode rod
- B.Sediment on the tank bottom; flush the tank on a schedule✓ Answer
- C.A cracked upper element; raise the thermostat and retest it
- D.A stuck relief valve; change the valve and lower the setting
Mineral sediment settles on the tank bottom and insulates it, so water trapped underneath flashes to steam and makes the popping sound while the tank runs hotter and wears out sooner. Periodic flushing removes the deposit, and the anode rod is inspected during the same visit.
Source: NAAEI CAMT curriculum, Plumbing Maintenance and Repair — water heater preventive maintenanceReport a problem with this question
18. A copper supply line has to be joined to an existing galvanized steel pipe. What does the connection require, and why?
- A.A solvent-welded coupling, to isolate the two metals from each other
- B.A soldered adapter, to bond the two metals into one current path
- C.A compression fitting, to seal the threads without tape or dope
- D.A dielectric union, to prevent galvanic corrosion at the joint✓ Answer
Two dissimilar metals in contact with water between them form a cell in which the more active metal corrodes away, and the joint fails from the inside. A dielectric union puts a non-conductive separator between them. Solvent cement bonds plastics only and will not join metal pipe.
Source: Model plumbing code general principle — dielectric separation of dissimilar metalsReport a problem with this question
19. Which practice BEST protects an exposed hose bibb and unheated utility-closet piping from freeze damage?
- A.Isolate and drain the exposed lines, then insulate them before winter✓ Answer
- B.Close every angle stop inside the apartment for the whole winter
- C.Raise the water heater thermostat to warm the entire piping system
- D.Run hot water through the hose bibb once on each cold morning
Water expands as it freezes, and a line with no water in it cannot burst. Shutting the interior valve, draining the exposed section, and adding insulation and a cover removes the water and slows heat loss. Hot water in a pipe cools quickly and does nothing overnight.
Source: NAAEI CAMT curriculum, Plumbing Maintenance and Repair — freeze protection and winterizationReport a problem with this question
20. A resident has left a hose connected to a laundry faucet with its free end lying in a full utility sink. Why is this a problem?
- A.A drop in supply pressure could siphon the waste water back✓ Answer
- B.The faucet aerator will clog from debris in the standing water
- C.Water standing in the hose will freeze and split the hose wall
- D.The weight of the hose can crack the faucet body at its base
A hose end submerged in used water is a cross-connection: if pressure in the supply falls, the line can draw that water back into the potable system. Protection comes from keeping an air gap above the flood level rim or fitting the outlet with a vacuum breaker.
Source: Model plumbing code general principle — cross-connection controlReport a problem with this question
21. While on an unrelated work order, a technician finds a soft, stained ceiling patch directly under an upstairs bathroom. What is the correct action?
- A.Wait a week to see whether the stained area spreads further
- B.Report it right away and begin drying the area the same day✓ Answer
- C.Tell the resident to keep a fan running on it for a few days
- D.Paint over the stain and note the paint color on the ticket
Wet building materials support mold growth within a day or two, so the window for drying is short and waiting makes a plumbing repair into a remediation job. The technician reports the finding, gets the water source above stopped, starts drying, and documents it rather than covering it up.
Source: NAAEI CAMT curriculum, Plumbing Maintenance and Repair — water intrusion response and reportingReport a problem with this question

Practice questions based on the published NAAEI CAMT domains — Essential Trade Skills, Compliance, Facilities Operations, and Professional Development & Collaboration — and on standard trade practice. CAMT and NAAEI are marks of the National Apartment Association; this site is not affiliated with or endorsed by NAA or NAAEI. Code requirements, licensing boundaries and permit rules vary by jurisdiction and revise on a cycle, so none is tested here as a recalled figure — always verify the code having jurisdiction and use a licensed contractor where the work requires one. Confirm current program requirements with NAAEI before testing. About the CAMT credential →

1. A fixture's drain vent connects to the drain line downstream of the trap. What is the vent's MAIN function?

2. A resident reports a sewer smell near the tub in a guest bathroom that is almost never used. The tub drains normally. What is the MOST likely cause?

3. A kitchen sink drains slowly, and a nearby fixture gurgles each time it drains. What does this pattern MOST likely indicate?

4. A resident reports that water rises in the tub whenever the toilet is flushed. Which system does this complaint belong to, and why?

5. Water is spraying from a supply line under a kitchen sink while the resident stands by. What should the technician do FIRST?

6. The angle stop under a leaking toilet is corroded and will not close all the way. What should the technician do NEXT?

7. A toilet refills by itself for a few seconds every several minutes although no one is using it. What is the MOST likely cause?

8. Water keeps appearing on the floor around a toilet that rocks slightly when it is used. What is the correct repair?

9. A toilet flushes weakly, yet the tank fills to its marked line and no other fixture in the unit is affected. What should be checked FIRST?

10. A single-handle faucet whose handle rotates a slotted metal ball over rubber seats and springs is which type of faucet?

11. A resident reports weak flow at one bathroom faucet only; every other fixture in the apartment is normal. What is the MOST likely cause?

12. A flange plunger has not cleared an object blocking a toilet. Which tool is the appropriate NEXT choice?

13. Why should a technician avoid clearing a slow apartment drain with a chemical drain opener?

14. A first-floor tub backs up every time the apartment above it drains. What does this MOST likely indicate?

15. A storage water heater's temperature and pressure relief valve is dripping steadily. What is the correct response?

16. An electric storage water heater has just been installed and its piping connected. What must happen BEFORE power is restored to it?

17. A storage water heater rumbles and pops during a heating cycle. What is the MOST likely cause and the correct preventive action?

18. A copper supply line has to be joined to an existing galvanized steel pipe. What does the connection require, and why?

19. Which practice BEST protects an exposed hose bibb and unheated utility-closet piping from freeze damage?

20. A resident has left a hose connected to a laundry faucet with its free end lying in a full utility sink. Why is this a problem?

21. While on an unrelated work order, a technician finds a soft, stained ceiling patch directly under an upstairs bathroom. What is the correct action?