UA STAR PLUMBING MASTERY
CERTIFICATION EXAM QUESTION AND
CORRECT ANSWERS (VERIFIED
ANSWERS) PLUS RATIONALES 2026 Q&A
INSTANT DOWNLOAD PDF
1. A DWV system stands for:
A. Drain-Waste-Vent
B. Domestic Water Valve
C. Drainage With Vacuum
D. Dual Water Vent
Rationale: The DWV system carries wastewater and air to prevent traps
from siphoning._
2. The minimum slope for a 4-inch horizontal drain is:
A. 1⁄8 inch per foot
B. 1⁄4 inch per foot
C. 1⁄2 inch per foot
D. 3⁄4 inch per foot
Rationale: Plumbing codes require a 1⁄4”/ft slope for 4” drains to
maintain flow without clogging._
3. A P-trap is used to:
A. Increase water pressure
B. Prevent sewer gas from entering the building
C. Balance hot and cold water
D. Connect water heater elements
Rationale: P-traps hold water to block sewer gas._
4. The standard water heater relief valve setting is:
A. 100 psi
, B. 150 psi
C. 200 psi
D. 250 psi
Rationale: Most residential relief valves are rated at 150 psi._
5. CPVC is primarily used for:
A. Gas piping
B. Hot and cold potable water
C. Drainage only
D. Electrical conduits
Rationale: CPVC withstands higher temperature water safely._
6. Backflow is prevented by a:
A. P-trap
B. Check valve
C. Flow restrictor
D. Pressure reducer
Rationale: Check valves stop reverse flow of water._
7. The fixture unit is a measurement of:
A. Water temperature
B. Drainage load
C. Air pressure
D. Flow velocity
Rationale: Fixture units help size plumbing drains and vents._
8. A vent pipe’s purpose is to:
A. Increase water temperature
B. Equalize pressure in the drain system
C. Filter wastewater
D. Add chemicals to water
Rationale: Vents allow air to prevent siphoning._
9. A trap arm connects:
A. Valve to faucet
B. Trap to vent
C. Water heater to main line
, D. Sump pump to sewer
Rationale: The trap arm carries waste to vented drain._
10.When soldering copper pipe, you should use:
A. PVC cement
B. Lead-free solder and flux
C. Thread seal tape
D. Rubber gaskets
Rationale: Lead-free solder is required for potable water._
11.A typical water service line size for a residential building is:
A. 1⁄2 inch
B. 3⁄4 inch
C. 2 inches
D. 4 inches
Rationale: 3⁄4” service is common for homes._
12.A ballcock is found in a:
A. Shower valve
B. Toilet tank
C. Floor drain
D. Hose bib
Rationale: Ballcocks control tank fill water in toilets._
13.To prevent corrosion, copper should not contact:
A. PVC
B. Concrete
C. Brass
D. Stainless steel
Rationale: Concrete induces corrosion on copper._
14.A union fitting is used to:
A. Change pipe direction
B. Allow disassembly
C. Measure pressure
D. Reduce pipe size
Rationale: Unions let you separate piping easily._
CERTIFICATION EXAM QUESTION AND
CORRECT ANSWERS (VERIFIED
ANSWERS) PLUS RATIONALES 2026 Q&A
INSTANT DOWNLOAD PDF
1. A DWV system stands for:
A. Drain-Waste-Vent
B. Domestic Water Valve
C. Drainage With Vacuum
D. Dual Water Vent
Rationale: The DWV system carries wastewater and air to prevent traps
from siphoning._
2. The minimum slope for a 4-inch horizontal drain is:
A. 1⁄8 inch per foot
B. 1⁄4 inch per foot
C. 1⁄2 inch per foot
D. 3⁄4 inch per foot
Rationale: Plumbing codes require a 1⁄4”/ft slope for 4” drains to
maintain flow without clogging._
3. A P-trap is used to:
A. Increase water pressure
B. Prevent sewer gas from entering the building
C. Balance hot and cold water
D. Connect water heater elements
Rationale: P-traps hold water to block sewer gas._
4. The standard water heater relief valve setting is:
A. 100 psi
, B. 150 psi
C. 200 psi
D. 250 psi
Rationale: Most residential relief valves are rated at 150 psi._
5. CPVC is primarily used for:
A. Gas piping
B. Hot and cold potable water
C. Drainage only
D. Electrical conduits
Rationale: CPVC withstands higher temperature water safely._
6. Backflow is prevented by a:
A. P-trap
B. Check valve
C. Flow restrictor
D. Pressure reducer
Rationale: Check valves stop reverse flow of water._
7. The fixture unit is a measurement of:
A. Water temperature
B. Drainage load
C. Air pressure
D. Flow velocity
Rationale: Fixture units help size plumbing drains and vents._
8. A vent pipe’s purpose is to:
A. Increase water temperature
B. Equalize pressure in the drain system
C. Filter wastewater
D. Add chemicals to water
Rationale: Vents allow air to prevent siphoning._
9. A trap arm connects:
A. Valve to faucet
B. Trap to vent
C. Water heater to main line
, D. Sump pump to sewer
Rationale: The trap arm carries waste to vented drain._
10.When soldering copper pipe, you should use:
A. PVC cement
B. Lead-free solder and flux
C. Thread seal tape
D. Rubber gaskets
Rationale: Lead-free solder is required for potable water._
11.A typical water service line size for a residential building is:
A. 1⁄2 inch
B. 3⁄4 inch
C. 2 inches
D. 4 inches
Rationale: 3⁄4” service is common for homes._
12.A ballcock is found in a:
A. Shower valve
B. Toilet tank
C. Floor drain
D. Hose bib
Rationale: Ballcocks control tank fill water in toilets._
13.To prevent corrosion, copper should not contact:
A. PVC
B. Concrete
C. Brass
D. Stainless steel
Rationale: Concrete induces corrosion on copper._
14.A union fitting is used to:
A. Change pipe direction
B. Allow disassembly
C. Measure pressure
D. Reduce pipe size
Rationale: Unions let you separate piping easily._
