Kansas Master Plumber Examination
Questions And Correct Answers
(Verified Answers) Plus Rationales
2026 Q&A | Instant Download Pdf
1.
Which plumbing principle is most important when designing a sanitary
drainage system?
A. Maximize pipe velocity
B. Provide adequate drainage, venting, and protection of the potable
water supply
C. Eliminate all cleanouts
D. Use the smallest possible pipe
Answer: B. Provide adequate drainage, venting, and protection of
the potable water supply
Rationale: A properly designed plumbing system must safely convey
sewage and waste, maintain trap seals through adequate venting, and
prevent contamination of potable water. Pipe sizing, slope, cleanouts,
and materials are all parts of achieving these objectives.
2.
What is the primary function of a plumbing trap?
A. Increase water pressure
B. Prevent sewer gases from entering a building
C. Increase drainage velocity
D. Reduce pipe diameter
,Answer: B. Prevent sewer gases from entering a building
Rationale: A trap retains a water seal that separates the occupied space
from the drainage system. The water seal prevents sewer gases and
odors from entering the building while still allowing wastewater to
discharge.
3.
Which fitting is generally preferred when changing direction in a
horizontal drainage system?
A. Sanitary tee installed horizontally
B. Long-sweep fitting
C. Vent tee
D. Straight coupling
Answer: B. Long-sweep fitting
Rationale: Drainage fittings should promote smooth flow and reduce
turbulence and blockage potential. Long-sweep fittings provide a
gradual change in direction and are generally preferred for horizontal
drainage changes of direction.
4.
What is the purpose of a cleanout?
A. Supply drinking water
B. Provide access for clearing a drainage obstruction
C. Increase water temperature
D. Prevent backflow
Answer: B. Provide access for clearing a drainage obstruction
Rationale: Cleanouts provide access to the drainage piping so that
stoppages can be located and removed. Proper placement is especially
,important on building drains, horizontal branches, and changes in
direction.
5.
A plumbing vent primarily protects what component of a drainage
system?
A. Water heater burner
B. Trap seal
C. Water meter
D. Pressure regulator
Answer: B. Trap seal
Rationale: Venting allows air to enter or leave the drainage system as
wastewater flows. This helps prevent excessive pressure fluctuations
that could siphon or blow the water out of fixture traps.
6.
What condition can occur when a drainage pipe is installed with
excessive slope?
A. Increased water temperature
B. Liquids may outrun solids
C. The pipe becomes a vent
D. The trap seal automatically increases
Answer: B. Liquids may outrun solids
Rationale: Excessive slope can allow liquid to move rapidly while
solids remain behind, increasing the possibility of deposits and
blockages. Drainage systems are designed around controlled slopes
that promote self-scouring flow.
7.
, What is the primary concern when installing potable water piping near
sanitary drainage piping?
A. Color matching
B. Cross-connection and contamination
C. Pipe insulation appearance
D. Drainage velocity
Answer: B. Cross-connection and contamination
Rationale: Potable water must be protected from contamination by
sewage or other nonpotable substances. Proper separation, backflow
protection, approved connections, and appropriate piping
arrangements are essential.
8.
What device is commonly used to protect potable water against back-
siphonage?
A. Trap primer
B. Air gap
C. Cleanout
D. Expansion tank
Answer: B. Air gap
Rationale: An air gap provides a physical separation between the
potable water outlet and the receiving vessel or flood-level rim.
Because there is no direct connection, back-siphonage cannot transmit
contamination across the gap.
9.
What is backflow?
Questions And Correct Answers
(Verified Answers) Plus Rationales
2026 Q&A | Instant Download Pdf
1.
Which plumbing principle is most important when designing a sanitary
drainage system?
A. Maximize pipe velocity
B. Provide adequate drainage, venting, and protection of the potable
water supply
C. Eliminate all cleanouts
D. Use the smallest possible pipe
Answer: B. Provide adequate drainage, venting, and protection of
the potable water supply
Rationale: A properly designed plumbing system must safely convey
sewage and waste, maintain trap seals through adequate venting, and
prevent contamination of potable water. Pipe sizing, slope, cleanouts,
and materials are all parts of achieving these objectives.
2.
What is the primary function of a plumbing trap?
A. Increase water pressure
B. Prevent sewer gases from entering a building
C. Increase drainage velocity
D. Reduce pipe diameter
,Answer: B. Prevent sewer gases from entering a building
Rationale: A trap retains a water seal that separates the occupied space
from the drainage system. The water seal prevents sewer gases and
odors from entering the building while still allowing wastewater to
discharge.
3.
Which fitting is generally preferred when changing direction in a
horizontal drainage system?
A. Sanitary tee installed horizontally
B. Long-sweep fitting
C. Vent tee
D. Straight coupling
Answer: B. Long-sweep fitting
Rationale: Drainage fittings should promote smooth flow and reduce
turbulence and blockage potential. Long-sweep fittings provide a
gradual change in direction and are generally preferred for horizontal
drainage changes of direction.
4.
What is the purpose of a cleanout?
A. Supply drinking water
B. Provide access for clearing a drainage obstruction
C. Increase water temperature
D. Prevent backflow
Answer: B. Provide access for clearing a drainage obstruction
Rationale: Cleanouts provide access to the drainage piping so that
stoppages can be located and removed. Proper placement is especially
,important on building drains, horizontal branches, and changes in
direction.
5.
A plumbing vent primarily protects what component of a drainage
system?
A. Water heater burner
B. Trap seal
C. Water meter
D. Pressure regulator
Answer: B. Trap seal
Rationale: Venting allows air to enter or leave the drainage system as
wastewater flows. This helps prevent excessive pressure fluctuations
that could siphon or blow the water out of fixture traps.
6.
What condition can occur when a drainage pipe is installed with
excessive slope?
A. Increased water temperature
B. Liquids may outrun solids
C. The pipe becomes a vent
D. The trap seal automatically increases
Answer: B. Liquids may outrun solids
Rationale: Excessive slope can allow liquid to move rapidly while
solids remain behind, increasing the possibility of deposits and
blockages. Drainage systems are designed around controlled slopes
that promote self-scouring flow.
7.
, What is the primary concern when installing potable water piping near
sanitary drainage piping?
A. Color matching
B. Cross-connection and contamination
C. Pipe insulation appearance
D. Drainage velocity
Answer: B. Cross-connection and contamination
Rationale: Potable water must be protected from contamination by
sewage or other nonpotable substances. Proper separation, backflow
protection, approved connections, and appropriate piping
arrangements are essential.
8.
What device is commonly used to protect potable water against back-
siphonage?
A. Trap primer
B. Air gap
C. Cleanout
D. Expansion tank
Answer: B. Air gap
Rationale: An air gap provides a physical separation between the
potable water outlet and the receiving vessel or flood-level rim.
Because there is no direct connection, back-siphonage cannot transmit
contamination across the gap.
9.
What is backflow?
