TEXAS MASTER PLUMBER EXAM – 100 MOST
TESTED QUESTIONS WITH VERIFIED ANSWERS &
RATIONALES | LATEST 2026–2027 EDITION | INSTANT
PDF DOWNLOAD
Question 1:
Which type of pipe is most commonly used for residential water supply lines?
A. PVC
B. Copper
C. Cast Iron
D. Galvanized Steel
Rationale: Copper is durable, corrosion-resistant, and widely used in residential
plumbing.
Question 2:
What is the minimum slope required for a 2-inch horizontal drain line according to
plumbing codes?
A. 1/16 inch per foot
B. 1/4 inch per foot
C. 1/8 inch per foot
D. 1/2 inch per foot
Rationale: Proper slope ensures adequate drainage and prevents clogging.
Question 3:
________ is used to prevent backflow of contaminated water into the potable water
system.
A. Pressure regulator
B. Backflow preventer
C. Check valve
D. Gate valve
Rationale: Backflow preventers protect drinking water from contamination.
Question 4:
Which fixture requires a trap?
A. Water heater
B. Sink
C. Expansion tank
,D. Hose bib
Rationale: Traps prevent sewer gases from entering buildings.
Question 5:
The standard residential water pressure should not exceed ______ psi.
A. 80
B. 60
C. 100
D. 120
Rationale: Excessive pressure can damage plumbing systems.
Question 6:
Which of the following fittings is used to connect two pipes at an angle?
A. Coupling
B. Elbow
C. Tee
D. Reducer
Rationale: Elbows are used to change pipe direction.
Question 7:
What type of venting prevents siphoning of a trap in plumbing systems?
A. Relief vent
B. Vent stack
C. Air admittance valve
D. Circuit vent
Rationale: Venting maintains proper pressure and prevents traps from emptying.
Question 8:
The main shutoff valve in a house is typically located:
A. Inside the attic
B. Near the water heater
C. At the point where water enters the building
D. In the garage
Rationale: The main shutoff stops water supply for the entire building.
Question 9:
Which pipe material is generally used for underground drainage?
A. Copper
B. Galvanized Steel
C. PVC
, D. PEX
Rationale: PVC is corrosion-resistant, durable, and suitable for underground
drainage.
Question 10:
________ is required to relieve thermal expansion in a closed water system.
A. Trap
B. Expansion tank
C. Check valve
D. Pressure-reducing valve
Rationale: Expansion tanks absorb excess pressure caused by heated water
expansion.
Question 11:
Which device prevents water hammer in plumbing systems?
A. Gate valve
B. Check valve
C. Air chamber or water hammer arrestor
D. Pressure regulator
Rationale: Air chambers absorb shock from sudden water stoppage, preventing
pipe damage.
Question 12:
What is the primary purpose of a P-trap?
A. Increase water pressure
B. Direct water flow
C. Prevent sewer gases from entering the building
D. Filter debris
Rationale: The P-trap retains water, forming a barrier against sewer gases.
Question 13:
A 3-inch sewer line requires a minimum slope of:
A. 1/8 inch per foot
B. 1/16 inch per foot
C. 1/4 inch per foot
D. 1/2 inch per foot
Rationale: Proper slope ensures gravity drainage for larger diameter pipes.
Question 14:
Which type of valve allows flow in only one direction?
TESTED QUESTIONS WITH VERIFIED ANSWERS &
RATIONALES | LATEST 2026–2027 EDITION | INSTANT
PDF DOWNLOAD
Question 1:
Which type of pipe is most commonly used for residential water supply lines?
A. PVC
B. Copper
C. Cast Iron
D. Galvanized Steel
Rationale: Copper is durable, corrosion-resistant, and widely used in residential
plumbing.
Question 2:
What is the minimum slope required for a 2-inch horizontal drain line according to
plumbing codes?
A. 1/16 inch per foot
B. 1/4 inch per foot
C. 1/8 inch per foot
D. 1/2 inch per foot
Rationale: Proper slope ensures adequate drainage and prevents clogging.
Question 3:
________ is used to prevent backflow of contaminated water into the potable water
system.
A. Pressure regulator
B. Backflow preventer
C. Check valve
D. Gate valve
Rationale: Backflow preventers protect drinking water from contamination.
Question 4:
Which fixture requires a trap?
A. Water heater
B. Sink
C. Expansion tank
,D. Hose bib
Rationale: Traps prevent sewer gases from entering buildings.
Question 5:
The standard residential water pressure should not exceed ______ psi.
A. 80
B. 60
C. 100
D. 120
Rationale: Excessive pressure can damage plumbing systems.
Question 6:
Which of the following fittings is used to connect two pipes at an angle?
A. Coupling
B. Elbow
C. Tee
D. Reducer
Rationale: Elbows are used to change pipe direction.
Question 7:
What type of venting prevents siphoning of a trap in plumbing systems?
A. Relief vent
B. Vent stack
C. Air admittance valve
D. Circuit vent
Rationale: Venting maintains proper pressure and prevents traps from emptying.
Question 8:
The main shutoff valve in a house is typically located:
A. Inside the attic
B. Near the water heater
C. At the point where water enters the building
D. In the garage
Rationale: The main shutoff stops water supply for the entire building.
Question 9:
Which pipe material is generally used for underground drainage?
A. Copper
B. Galvanized Steel
C. PVC
, D. PEX
Rationale: PVC is corrosion-resistant, durable, and suitable for underground
drainage.
Question 10:
________ is required to relieve thermal expansion in a closed water system.
A. Trap
B. Expansion tank
C. Check valve
D. Pressure-reducing valve
Rationale: Expansion tanks absorb excess pressure caused by heated water
expansion.
Question 11:
Which device prevents water hammer in plumbing systems?
A. Gate valve
B. Check valve
C. Air chamber or water hammer arrestor
D. Pressure regulator
Rationale: Air chambers absorb shock from sudden water stoppage, preventing
pipe damage.
Question 12:
What is the primary purpose of a P-trap?
A. Increase water pressure
B. Direct water flow
C. Prevent sewer gases from entering the building
D. Filter debris
Rationale: The P-trap retains water, forming a barrier against sewer gases.
Question 13:
A 3-inch sewer line requires a minimum slope of:
A. 1/8 inch per foot
B. 1/16 inch per foot
C. 1/4 inch per foot
D. 1/2 inch per foot
Rationale: Proper slope ensures gravity drainage for larger diameter pipes.
Question 14:
Which type of valve allows flow in only one direction?
