NGWA CERTIFIED PUMP INSTALLER (CPI)
– 100 QUESTION PRACTICE EXAM
QUESTIONS AND CORRECT ANSWERS
(VERIFIED ANSWERS) PLUS RATIONALES
2026 Q&A | INSTANT DOWNLOAD PDF
Section 1: Groundwater Hydraulics and Well Performance (Q 1-15)
1. What is the definition of "drawdown" in a pumping well?
A. The total depth of the well from surface to bottom
B. The volume of water stored in the well casing per foot
C. The difference between the static water level and the pumping water
level
D. The maximum rate at which water flows from the pump
Correct Answer: C
Rationale: Drawdown is the measured lowering of the water level in a
well due to pumping. It is specifically calculated as the pumping water
level minus the static water level .
2. A well log shows a static water level (SWL) of 50 feet and a
pumping water level (PWL) of 80 feet. What is the drawdown?
A. 30 feet
B. 50 feet
C. 80 feet
D. 130 feet
,Correct Answer: A
Rationale: Drawdown = PWL – SWL (80 ft – 50 ft = 30 ft). This value
is critical for calculating Total Dynamic Head (TDH) .
3. What is the primary cause of "screen incrustation" in a water
well?
A. High pumping speed
B. Chemical precipitation (scale) or bacterial growth
C. Oversized gravel pack
D. Incorrect pump alignment
Correct Answer: B
Rationale: Incrustation refers to the buildup of scale (calcium
carbonate, iron) or iron bacteria on the screen openings. This reduces the
well's effective open area, leading to reduced yield over time .
4. According to standard design recommendations, what is the
maximum recommended intake velocity for a well screen?
A. 5 feet per second
B. Less than 0.1 feet per second
C. Less than 1 foot per second
D. 10 feet per second
Correct Answer: B
Rationale: To minimize sand pumping, friction losses, and biofouling,
the entrance velocity through a well screen should generally be kept
below 0.1 ft/s (approximately 1.5 gpm per square inch of open area) .
5. Which type of rock formation is the LEAST likely to yield
sufficient water for a domestic well?
A. Sandstone
B. Limestone
,C. Granite (Fractured)
D. Shale
Correct Answer: C
Rationale: While fractured granite can yield water, unfractured igneous
rocks like granite are generally very dense and impermeable, making
them unreliable water sources compared to porous sedimentary rocks
like sandstone or limestone .
6. A pump is operating at 50 gallons per minute (GPM). If you
increase the pipe diameter, what happens to the friction loss?
A. Friction loss increases
B. Friction loss decreases
C. Friction loss remains the same
D. Friction loss becomes zero
Correct Answer: B
Rationale: Friction loss is inversely proportional to the pipe diameter
(to the 5th power in the Hazen-Williams formula). Larger diameters
mean lower water velocity and significantly less friction .
7. What does "specific capacity" of a well refer to?
A. The total horsepower of the pump motor
B. The yield per unit of drawdown (GPM/ft)
C. The maximum depth the pump can sit
D. The voltage required for the motor
Correct Answer: B
Rationale: Specific capacity is a measure of well efficiency. It is
calculated by dividing the pumping rate (GPM) by the drawdown (feet).
A declining specific capacity over time indicates well fouling or screen
plugging.
, 8. Where is over 90% of readily available fresh water located?
A. Lakes and rivers
B. Polar ice caps
C. Underground (Groundwater)
D. The atmosphere
Correct Answer: C
Rationale: Excluding water locked in ice caps, groundwater represents
over 90% of the Earth's liquid fresh water, making it a critical resource
for wells .
9. What is "artesian pressure"?
A. Pressure created by a jet pump
B. Vacuum pressure inside the drop pipe
C. Pressure from confined groundwater due to gravity (elevation head)
D. Pressure caused by water hammer
Correct Answer: C
Rationale: Artesian conditions occur when a confined aquifer is under
pressure greater than atmospheric pressure. When a well taps this
aquifer, water rises above the top of the aquifer (and potentially above
ground level) without pumping .
10. What are the three main classifications of rock types?
A. Sand, Gravel, Clay
B. Basalt, Granite, Pumice
C. Igneous, Sedimentary, Metamorphic
D. Shale, Sandstone, Limestone
Correct Answer: C
Rationale: All rocks are geologically classified into these three families.
Sedimentary (sandstone, limestone) are most important for water supply
due to their porosity .
– 100 QUESTION PRACTICE EXAM
QUESTIONS AND CORRECT ANSWERS
(VERIFIED ANSWERS) PLUS RATIONALES
2026 Q&A | INSTANT DOWNLOAD PDF
Section 1: Groundwater Hydraulics and Well Performance (Q 1-15)
1. What is the definition of "drawdown" in a pumping well?
A. The total depth of the well from surface to bottom
B. The volume of water stored in the well casing per foot
C. The difference between the static water level and the pumping water
level
D. The maximum rate at which water flows from the pump
Correct Answer: C
Rationale: Drawdown is the measured lowering of the water level in a
well due to pumping. It is specifically calculated as the pumping water
level minus the static water level .
2. A well log shows a static water level (SWL) of 50 feet and a
pumping water level (PWL) of 80 feet. What is the drawdown?
A. 30 feet
B. 50 feet
C. 80 feet
D. 130 feet
,Correct Answer: A
Rationale: Drawdown = PWL – SWL (80 ft – 50 ft = 30 ft). This value
is critical for calculating Total Dynamic Head (TDH) .
3. What is the primary cause of "screen incrustation" in a water
well?
A. High pumping speed
B. Chemical precipitation (scale) or bacterial growth
C. Oversized gravel pack
D. Incorrect pump alignment
Correct Answer: B
Rationale: Incrustation refers to the buildup of scale (calcium
carbonate, iron) or iron bacteria on the screen openings. This reduces the
well's effective open area, leading to reduced yield over time .
4. According to standard design recommendations, what is the
maximum recommended intake velocity for a well screen?
A. 5 feet per second
B. Less than 0.1 feet per second
C. Less than 1 foot per second
D. 10 feet per second
Correct Answer: B
Rationale: To minimize sand pumping, friction losses, and biofouling,
the entrance velocity through a well screen should generally be kept
below 0.1 ft/s (approximately 1.5 gpm per square inch of open area) .
5. Which type of rock formation is the LEAST likely to yield
sufficient water for a domestic well?
A. Sandstone
B. Limestone
,C. Granite (Fractured)
D. Shale
Correct Answer: C
Rationale: While fractured granite can yield water, unfractured igneous
rocks like granite are generally very dense and impermeable, making
them unreliable water sources compared to porous sedimentary rocks
like sandstone or limestone .
6. A pump is operating at 50 gallons per minute (GPM). If you
increase the pipe diameter, what happens to the friction loss?
A. Friction loss increases
B. Friction loss decreases
C. Friction loss remains the same
D. Friction loss becomes zero
Correct Answer: B
Rationale: Friction loss is inversely proportional to the pipe diameter
(to the 5th power in the Hazen-Williams formula). Larger diameters
mean lower water velocity and significantly less friction .
7. What does "specific capacity" of a well refer to?
A. The total horsepower of the pump motor
B. The yield per unit of drawdown (GPM/ft)
C. The maximum depth the pump can sit
D. The voltage required for the motor
Correct Answer: B
Rationale: Specific capacity is a measure of well efficiency. It is
calculated by dividing the pumping rate (GPM) by the drawdown (feet).
A declining specific capacity over time indicates well fouling or screen
plugging.
, 8. Where is over 90% of readily available fresh water located?
A. Lakes and rivers
B. Polar ice caps
C. Underground (Groundwater)
D. The atmosphere
Correct Answer: C
Rationale: Excluding water locked in ice caps, groundwater represents
over 90% of the Earth's liquid fresh water, making it a critical resource
for wells .
9. What is "artesian pressure"?
A. Pressure created by a jet pump
B. Vacuum pressure inside the drop pipe
C. Pressure from confined groundwater due to gravity (elevation head)
D. Pressure caused by water hammer
Correct Answer: C
Rationale: Artesian conditions occur when a confined aquifer is under
pressure greater than atmospheric pressure. When a well taps this
aquifer, water rises above the top of the aquifer (and potentially above
ground level) without pumping .
10. What are the three main classifications of rock types?
A. Sand, Gravel, Clay
B. Basalt, Granite, Pumice
C. Igneous, Sedimentary, Metamorphic
D. Shale, Sandstone, Limestone
Correct Answer: C
Rationale: All rocks are geologically classified into these three families.
Sedimentary (sandstone, limestone) are most important for water supply
due to their porosity .
