Arizona AZ L-91 Irrigation
Systems Contractor Practice
Exam | Questions, Verified
Answers & Detailed
Rationales | Complete
Contractor License Exam Prep
Study Guide | Updated 2026
1. What is the primary purpose of an irrigation system?
A. Increase soil compaction
B. Apply water to landscape plants in a controlled manner
C. Eliminate the need for drainage
D. Prevent all evaporation
Correct answer: Apply water to landscape plants in a
controlled manner
Rationale: Irrigation systems are designed to deliver
water to plant root zones at appropriate rates,
quantities, and frequencies while promoting efficient
water use.
2. Which measurement is commonly used to describe
water pressure?
A. Gallons per minute
B. Feet per second
C. Pounds per square inch
D. Cubic feet
Correct answer: Pounds per square inch
Rationale: PSI, or pounds per square inch, is the
standard measurement commonly used for water
pressure in irrigation systems.
,3. What does GPM represent?
A. Gallons per meter
B. Gallons per minute
C. Ground pressure measurement
D. Gallons per manifold
Correct answer: Gallons per minute
Rationale: GPM measures the volume of water flowing
through a system or component during one minute.
4. Which component controls the flow of water into an
irrigation zone?
A. Sprinkler head
B. Valve
C. Pressure gauge
D. Pipe hanger
Correct answer: Valve
Rationale: An irrigation control valve opens and closes
to regulate water flow to an individual zone or group of
zones.
5. What is the primary purpose of an irrigation
controller?
A. Increase pipe diameter
B. Automatically operate irrigation valves according to
programmed schedules
C. Increase static water pressure
D. Filter all sediment from the water supply
Correct answer: Automatically operate irrigation valves
according to programmed schedules
Rationale: Controllers send electrical signals to zone
valves, allowing irrigation to operate automatically
according to programmed watering times and durations.
6. What is static water pressure?
,A. Pressure while water is flowing
B. Pressure measured when water is not flowing
C. Pressure after a sprinkler head
D. Pressure inside a drain
Correct answer: Pressure measured when water is not
flowing
Rationale: Static pressure is the pressure in a water
supply when there is no flow through the system.
7. What is dynamic or residual pressure?
A. Pressure measured while water is flowing
B. Pressure with the main valve closed
C. Atmospheric pressure
D. Pressure inside an empty pipe
Correct answer: Pressure measured while water is
flowing
Rationale: Dynamic pressure is the pressure remaining
in the system while water is moving. It is particularly
important when sizing irrigation systems.
8. What generally happens to pressure when water
flows through a pipe?
A. It always increases
B. It remains exactly constant
C. It decreases because of friction and other losses
D. It becomes atmospheric pressure
Correct answer: It decreases because of friction and
other losses
Rationale: Pipe friction, fittings, elevation changes,
valves, and other components cause pressure losses as
water moves through an irrigation system.
9. Which factor generally increases friction loss in an
irrigation pipe?
, A. Increasing pipe diameter
B. Increasing pipe length
C. Reducing water velocity
D. Reducing flow rate
Correct answer: Increasing pipe length
Rationale: Longer pipe runs create greater friction loss.
Higher flow rates and smaller pipe diameters can also
substantially increase friction loss.
10. What is water velocity?
A. Water temperature
B. Speed at which water moves through a pipe
C. Pressure inside a closed pipe
D. Amount of water stored in a tank
Correct answer: Speed at which water moves through a
pipe
Rationale: Velocity describes the speed of water
movement through the piping system and is commonly
expressed in feet per second.
11. What is the purpose of a pressure regulator?
A. Increase electrical voltage
B. Maintain downstream water pressure within a desired range
C. Measure soil moisture
D. Increase pump horsepower
Correct answer: Maintain downstream water pressure
within a desired range
Rationale: Pressure regulators reduce excessive
upstream pressure and maintain a more consistent
downstream pressure suitable for irrigation equipment.
12. What is the purpose of a flow-control feature on an
irrigation valve?
A. Adjust the amount of water passing through the valve
B. Change electrical voltage
Systems Contractor Practice
Exam | Questions, Verified
Answers & Detailed
Rationales | Complete
Contractor License Exam Prep
Study Guide | Updated 2026
1. What is the primary purpose of an irrigation system?
A. Increase soil compaction
B. Apply water to landscape plants in a controlled manner
C. Eliminate the need for drainage
D. Prevent all evaporation
Correct answer: Apply water to landscape plants in a
controlled manner
Rationale: Irrigation systems are designed to deliver
water to plant root zones at appropriate rates,
quantities, and frequencies while promoting efficient
water use.
2. Which measurement is commonly used to describe
water pressure?
A. Gallons per minute
B. Feet per second
C. Pounds per square inch
D. Cubic feet
Correct answer: Pounds per square inch
Rationale: PSI, or pounds per square inch, is the
standard measurement commonly used for water
pressure in irrigation systems.
,3. What does GPM represent?
A. Gallons per meter
B. Gallons per minute
C. Ground pressure measurement
D. Gallons per manifold
Correct answer: Gallons per minute
Rationale: GPM measures the volume of water flowing
through a system or component during one minute.
4. Which component controls the flow of water into an
irrigation zone?
A. Sprinkler head
B. Valve
C. Pressure gauge
D. Pipe hanger
Correct answer: Valve
Rationale: An irrigation control valve opens and closes
to regulate water flow to an individual zone or group of
zones.
5. What is the primary purpose of an irrigation
controller?
A. Increase pipe diameter
B. Automatically operate irrigation valves according to
programmed schedules
C. Increase static water pressure
D. Filter all sediment from the water supply
Correct answer: Automatically operate irrigation valves
according to programmed schedules
Rationale: Controllers send electrical signals to zone
valves, allowing irrigation to operate automatically
according to programmed watering times and durations.
6. What is static water pressure?
,A. Pressure while water is flowing
B. Pressure measured when water is not flowing
C. Pressure after a sprinkler head
D. Pressure inside a drain
Correct answer: Pressure measured when water is not
flowing
Rationale: Static pressure is the pressure in a water
supply when there is no flow through the system.
7. What is dynamic or residual pressure?
A. Pressure measured while water is flowing
B. Pressure with the main valve closed
C. Atmospheric pressure
D. Pressure inside an empty pipe
Correct answer: Pressure measured while water is
flowing
Rationale: Dynamic pressure is the pressure remaining
in the system while water is moving. It is particularly
important when sizing irrigation systems.
8. What generally happens to pressure when water
flows through a pipe?
A. It always increases
B. It remains exactly constant
C. It decreases because of friction and other losses
D. It becomes atmospheric pressure
Correct answer: It decreases because of friction and
other losses
Rationale: Pipe friction, fittings, elevation changes,
valves, and other components cause pressure losses as
water moves through an irrigation system.
9. Which factor generally increases friction loss in an
irrigation pipe?
, A. Increasing pipe diameter
B. Increasing pipe length
C. Reducing water velocity
D. Reducing flow rate
Correct answer: Increasing pipe length
Rationale: Longer pipe runs create greater friction loss.
Higher flow rates and smaller pipe diameters can also
substantially increase friction loss.
10. What is water velocity?
A. Water temperature
B. Speed at which water moves through a pipe
C. Pressure inside a closed pipe
D. Amount of water stored in a tank
Correct answer: Speed at which water moves through a
pipe
Rationale: Velocity describes the speed of water
movement through the piping system and is commonly
expressed in feet per second.
11. What is the purpose of a pressure regulator?
A. Increase electrical voltage
B. Maintain downstream water pressure within a desired range
C. Measure soil moisture
D. Increase pump horsepower
Correct answer: Maintain downstream water pressure
within a desired range
Rationale: Pressure regulators reduce excessive
upstream pressure and maintain a more consistent
downstream pressure suitable for irrigation equipment.
12. What is the purpose of a flow-control feature on an
irrigation valve?
A. Adjust the amount of water passing through the valve
B. Change electrical voltage
