TCEQ IRRIGATION LICENSE Exam Prep
2026/2027 Complete Study Guide & Practice
Question
EXAM
Question 1
What is the minimum unobstructed vertical separation required for an approved air gap
if the water supply outlet has a diameter of 1 inch?
A) 1 inch
B) 1.5 inches
C) 2 inches
D) 2.5 inches
Answer: C) 2 inches
Rationale: An approved air gap must be at least twice the diameter of the supply outlet.
For a 1-inch outlet, 2 × 1" = 2 inches minimum separation.
Question 2
A Pressure Vacuum Breaker (PVB) is designed to protect against which of the following?
A) Backsiphonage only
B) Backpressure only
C) Both backsiphonage and backpressure
D) Low pressure conditions only
Answer: A) Backsiphonage only
Rationale: A PVB is designed to protect against backsiphonage ONLY. It cannot protect
against backpressure. This is why PVBs must not have shut-off valves downstream.
,Question 3
An Atmospheric Vacuum Breaker (AVB) must be installed a minimum of how many
inches above the highest downstream outlet?
A) 4 inches
B) 6 inches
C) 12 inches
D) 24 inches
Answer: B) 6 inches
Rationale: AVBs must be installed a minimum of 6 inches above the highest outlet,
sprinkler head, or piping they protect. They cannot be under continuous pressure for
more than 12 hours.
Question 4
Which backflow prevention device is approved for protection against both
backsiphonage and backpressure in high-hazard situations?
A) Atmospheric Vacuum Breaker (AVB)
B) Pressure Vacuum Breaker (PVB)
C) Double Check Valve Assembly (DCVA)
D) Reduced Pressure Zone Assembly (RPZ)
Answer: D) Reduced Pressure Zone Assembly (RPZ)
Rationale: RPZs are the only mechanical backflow preventers that provide protection
against both backsiphonage and backpressure in high-hazard (toxic) situations.
Question 5
A Double Check Valve Assembly (DCVA) is acceptable for protecting against:
,A) High health hazard cross-connections only
B) Low to moderate health hazard cross-connections only
C) All types of cross-connections regardless of hazard
D) Backsiphonage only
Answer: B) Low to moderate health hazard cross-connections only
Rationale: DCVAs are approved for low to moderate health hazard situations (pollutants)
but NOT for high health hazards (contaminants).
Question 6
What is the minimum test cock size required on a backflow prevention assembly?
A) 1/8 inch
B) 1/4 inch
C) 3/8 inch
D) 1/2 inch
Answer: B) 1/4 inch
Rationale: All test cocks on backflow prevention assemblies must be a minimum of 1/4
inch in size with threads compatible for testing equipment.
Question 7
When installing an RPZ assembly indoors, what is the minimum clearance required
below the assembly for drainage?
A) 6 inches
B) 12 inches
C) 18 inches
D) 24 inches
, Answer: D) 24 inches
Rationale: RPZs can discharge water when relieving. Indoor installations require a
minimum of 24 inches clearance below the assembly to allow for proper drainage and
prevent flooding.
Question 8
What is backpressure?
A) Pressure that pushes water back toward the city main
B) Pressure lower than atmospheric pressure
C) A siphon created by gravity
D) Pressure created by elevation changes only
Answer: A) Pressure that pushes water back toward the city main
Rationale: Backpressure occurs when downstream pressure exceeds supply pressure,
forcing water back toward the source. Common causes include pumps, elevation, or
thermal expansion.
Question 9
Which condition creates backsiphonage?
A) Downstream pressure exceeding supply pressure
B) A negative or reduced pressure in the supply line
C) High flow rates in the system
D) Thermal expansion in a water heater
Answer: B) A negative or reduced pressure in the supply line
Rationale: Backsiphonage is caused by negative pressure (vacuum or partial vacuum) in
2026/2027 Complete Study Guide & Practice
Question
EXAM
Question 1
What is the minimum unobstructed vertical separation required for an approved air gap
if the water supply outlet has a diameter of 1 inch?
A) 1 inch
B) 1.5 inches
C) 2 inches
D) 2.5 inches
Answer: C) 2 inches
Rationale: An approved air gap must be at least twice the diameter of the supply outlet.
For a 1-inch outlet, 2 × 1" = 2 inches minimum separation.
Question 2
A Pressure Vacuum Breaker (PVB) is designed to protect against which of the following?
A) Backsiphonage only
B) Backpressure only
C) Both backsiphonage and backpressure
D) Low pressure conditions only
Answer: A) Backsiphonage only
Rationale: A PVB is designed to protect against backsiphonage ONLY. It cannot protect
against backpressure. This is why PVBs must not have shut-off valves downstream.
,Question 3
An Atmospheric Vacuum Breaker (AVB) must be installed a minimum of how many
inches above the highest downstream outlet?
A) 4 inches
B) 6 inches
C) 12 inches
D) 24 inches
Answer: B) 6 inches
Rationale: AVBs must be installed a minimum of 6 inches above the highest outlet,
sprinkler head, or piping they protect. They cannot be under continuous pressure for
more than 12 hours.
Question 4
Which backflow prevention device is approved for protection against both
backsiphonage and backpressure in high-hazard situations?
A) Atmospheric Vacuum Breaker (AVB)
B) Pressure Vacuum Breaker (PVB)
C) Double Check Valve Assembly (DCVA)
D) Reduced Pressure Zone Assembly (RPZ)
Answer: D) Reduced Pressure Zone Assembly (RPZ)
Rationale: RPZs are the only mechanical backflow preventers that provide protection
against both backsiphonage and backpressure in high-hazard (toxic) situations.
Question 5
A Double Check Valve Assembly (DCVA) is acceptable for protecting against:
,A) High health hazard cross-connections only
B) Low to moderate health hazard cross-connections only
C) All types of cross-connections regardless of hazard
D) Backsiphonage only
Answer: B) Low to moderate health hazard cross-connections only
Rationale: DCVAs are approved for low to moderate health hazard situations (pollutants)
but NOT for high health hazards (contaminants).
Question 6
What is the minimum test cock size required on a backflow prevention assembly?
A) 1/8 inch
B) 1/4 inch
C) 3/8 inch
D) 1/2 inch
Answer: B) 1/4 inch
Rationale: All test cocks on backflow prevention assemblies must be a minimum of 1/4
inch in size with threads compatible for testing equipment.
Question 7
When installing an RPZ assembly indoors, what is the minimum clearance required
below the assembly for drainage?
A) 6 inches
B) 12 inches
C) 18 inches
D) 24 inches
, Answer: D) 24 inches
Rationale: RPZs can discharge water when relieving. Indoor installations require a
minimum of 24 inches clearance below the assembly to allow for proper drainage and
prevent flooding.
Question 8
What is backpressure?
A) Pressure that pushes water back toward the city main
B) Pressure lower than atmospheric pressure
C) A siphon created by gravity
D) Pressure created by elevation changes only
Answer: A) Pressure that pushes water back toward the city main
Rationale: Backpressure occurs when downstream pressure exceeds supply pressure,
forcing water back toward the source. Common causes include pumps, elevation, or
thermal expansion.
Question 9
Which condition creates backsiphonage?
A) Downstream pressure exceeding supply pressure
B) A negative or reduced pressure in the supply line
C) High flow rates in the system
D) Thermal expansion in a water heater
Answer: B) A negative or reduced pressure in the supply line
Rationale: Backsiphonage is caused by negative pressure (vacuum or partial vacuum) in
