Certificate of Qualification Plumber (CCQ)
Practice Exam Questions And Correct Answers
(Verified Answers) Plus Rationales 2026 Q&A |
Instant Download Pdf
1. What is the minimum slope required for a horizontal drainage
pipe to ensure proper flow?
a) 1/16 inch per foot
b) 1/8 inch per foot
c) 1/4 inch per foot
d) 1/2 inch per foot
Proper slope ensures gravity drainage and prevents stagnation in
the pipe.
2. Which material is commonly used for potable water supply lines in
residential plumbing?
a) PVC
b) Cast iron
c) Copper
d) Galvanized steel
Copper is durable, corrosion-resistant, and safe for drinking water.
3. What is the primary function of a trap in a plumbing system?
a) Increase water pressure
b) Prevent sewer gases from entering the building
c) Filter debris from water
d) Heat water before use
, Traps create a water seal that blocks gases while allowing waste
to pass.
4. What type of valve is best suited for throttling water flow?
a) Gate valve
b) Globe valve
c) Ball valve
d) Check valve
Globe valves allow precise flow control, unlike gate or ball valves.
5. When soldering copper pipes, what is essential for a strong joint?
a) Using water in the joint
b) Cleaning and fluxing the pipe and fitting
c) Applying heat unevenly
d) Tightening the fitting before soldering
Flux removes oxidation and helps solder flow evenly for a leak-free
joint.
6. Which of the following is a requirement for vent pipes?
a) Must be painted
b) Must extend above the roofline
c) Can be below ground
d) Must be larger than the drain pipe
Vents allow air into the drainage system and prevent siphoning of
traps.
7. What is the primary purpose of a pressure-reducing valve (PRV)?
a) Increase water flow
b) Filter impurities
c) Lower high incoming water pressure
, d) Mix hot and cold water
PRVs protect plumbing fixtures and piping from excessive pressure.
8. Which fixture requires an air gap to prevent backflow?
a) Toilet
b) Shower
c) Sink faucet
d) Water heater
An air gap prevents contaminated water from siphoning back into
potable water lines.
9. What is the recommended distance between supports for
horizontal copper tubing?
a) 1 foot
b) 2 feet
c) 3 feet
d) 5 feet
Proper support prevents sagging and potential joint stress.
10. A plumber notices water hammer when a valve closes
quickly. What device can mitigate this?
a) Ball valve
b) Gate valve
c) Water hammer arrestor
d) Pressure regulator
Water hammer arrestors absorb the shock from sudden water
stoppage.
11. When testing a DWV system, what pressure is typically used
for air testing?
a) 5 psi
Practice Exam Questions And Correct Answers
(Verified Answers) Plus Rationales 2026 Q&A |
Instant Download Pdf
1. What is the minimum slope required for a horizontal drainage
pipe to ensure proper flow?
a) 1/16 inch per foot
b) 1/8 inch per foot
c) 1/4 inch per foot
d) 1/2 inch per foot
Proper slope ensures gravity drainage and prevents stagnation in
the pipe.
2. Which material is commonly used for potable water supply lines in
residential plumbing?
a) PVC
b) Cast iron
c) Copper
d) Galvanized steel
Copper is durable, corrosion-resistant, and safe for drinking water.
3. What is the primary function of a trap in a plumbing system?
a) Increase water pressure
b) Prevent sewer gases from entering the building
c) Filter debris from water
d) Heat water before use
, Traps create a water seal that blocks gases while allowing waste
to pass.
4. What type of valve is best suited for throttling water flow?
a) Gate valve
b) Globe valve
c) Ball valve
d) Check valve
Globe valves allow precise flow control, unlike gate or ball valves.
5. When soldering copper pipes, what is essential for a strong joint?
a) Using water in the joint
b) Cleaning and fluxing the pipe and fitting
c) Applying heat unevenly
d) Tightening the fitting before soldering
Flux removes oxidation and helps solder flow evenly for a leak-free
joint.
6. Which of the following is a requirement for vent pipes?
a) Must be painted
b) Must extend above the roofline
c) Can be below ground
d) Must be larger than the drain pipe
Vents allow air into the drainage system and prevent siphoning of
traps.
7. What is the primary purpose of a pressure-reducing valve (PRV)?
a) Increase water flow
b) Filter impurities
c) Lower high incoming water pressure
, d) Mix hot and cold water
PRVs protect plumbing fixtures and piping from excessive pressure.
8. Which fixture requires an air gap to prevent backflow?
a) Toilet
b) Shower
c) Sink faucet
d) Water heater
An air gap prevents contaminated water from siphoning back into
potable water lines.
9. What is the recommended distance between supports for
horizontal copper tubing?
a) 1 foot
b) 2 feet
c) 3 feet
d) 5 feet
Proper support prevents sagging and potential joint stress.
10. A plumber notices water hammer when a valve closes
quickly. What device can mitigate this?
a) Ball valve
b) Gate valve
c) Water hammer arrestor
d) Pressure regulator
Water hammer arrestors absorb the shock from sudden water
stoppage.
11. When testing a DWV system, what pressure is typically used
for air testing?
a) 5 psi
