NGWA CERTIFIED PUMP INSTALLER (CPI) – 100 QUESTIONS AND CORRECT ANSWERS (VERIFIED ANSWERS)
PLUS RATIONALES 2026 Q&A | INSTANT DOWNLOAD PDF
Core Domains
1. Groundwater Hydraulics and Well Performance
2. Pump Types, Components, and Selection
3. Electrical Systems and Motor Controls
4. Plumbing, Piping, and Valves
5. Safety Practices and PPE
6. Regulations, Codes, and Legal Compliance
7. Troubleshooting, Diagnostics, and Repair
8. Water Quality, Treatment, and Contamination Prevention
*9. System Design, Installation, and Start-Up*
10. Ethics, Professional Conduct, and Customer Relations
Introduction
This assessment evaluates the knowledge and applied skills required for the NGWA Certified Pump Installer (CPI)
credential. Candidates will demonstrate mastery of groundwater hydraulics, pump selection, electrical systems,
safety protocols, regulatory compliance, troubleshooting, and professional ethics. Questions are multiple-choice
and scenario-based, emphasizing real-world decision-making during installation, diagnosis, and repair. Each
question includes a verified correct answer and a clear rationale. Success requires both theoretical understanding
and practical field judgment.
SECTION ONE: QUESTIONS 1–100
,1. A submersible pump is selected for a 6-inch diameter well with a static water level of 80 feet and a pumping
level of 150 feet. What is the minimum recommended pump housing diameter?
A. 4.5 inches
B. 5.0 inches
C. 5.5 inches
D. 3.9 inches
🟢D
🔴 RATIONALE: Pump housing must allow adequate annular space for cooling and sand settling; in a 6-inch
well, maximum pump diameter is 4.9 inches, so 3.9 inches is correct and safe.
2. A constant pressure system using a variable frequency drive (VFD) fails to maintain setpoint pressure under
varying flow. What is the most likely cause?
A. Pressure transducer is calibrated correctly
B. Motor nameplate horsepower exceeds drive rating
C. Drive is in hand mode instead of auto
D. Discharge check valve is fully open
🟢C
🔴 RATIONALE: Hand mode locks drive at fixed speed; auto mode allows VFD to adjust frequency based on
feedback from transducer to maintain pressure.
3. According to the National Electrical Code (NEC), what is the minimum burial depth for rigid metal conduit
(RMC) supplying a pump in a residential yard?
A. 6 inches
B. 12 inches
,C. 18 inches
D. 24 inches
🟢A
🔴 RATIONALE: NEC Table 300.5 allows RMC burial at 6 inches for residential locations; other conduits require
deeper depths.
4. A centrifugal pump operating against a closed discharge valve will experience:
A. Maximum flow and minimum power
B. Minimum flow and maximum temperature rise
C. Maximum efficiency and minimum pressure
D. Cavitation and vibration only
🟢B
🔴 RATIONALE: Closed valve = zero flow; recirculation heats water rapidly, causing potential pump damage if
prolonged.
5. You arrive at a site where the pump runs continuously but delivers very little water. Pressure gauge at the
tank reads 20 psi while pump is running. The most likely cause is:
A. Worn impeller or severe internal wear
B. Air-locked drop pipe
C. Closed gate valve after the tank
D. Oversized pressure switch differential
🟢A
🔴 RATIONALE: Low flow with running pump and low pressure typically indicates impeller wear, failed diffuser,
or severe internal recirculation.
, 6. Which of the following is the most appropriate first action when a pump installer discovers an unlabeled wire
in a control box?
A. Cap it and ignore
B. Apply voltage and test with a multimeter
C. Trace continuity back to source
D. Connect it to ground
🟢C
🔴 RATIONALE: Safety requires identifying unknown wires by continuity tracing before energizing to prevent
short circuits or electrocution.
7. A customer reports rusty water only after the pump shuts off. The well is 10 years old. What is the most
probable cause?
A. Galvanized drop pipe corrosion
B. Sand pumping from aquifer
C. Failure of bladder tank
D. Low water table
🟢A
🔴 RATIONALE: Rust after pump off indicates corrosion products settling; galvanized steel drop pipe commonly
fails this way, especially in aggressive water.
8. When lowering a submersible pump into a drilled well, the torque arrestor should be placed:
A. Directly above the pump motor
B. At the well seal
C. Midway up the drop pipe
D. Every 20 feet
PLUS RATIONALES 2026 Q&A | INSTANT DOWNLOAD PDF
Core Domains
1. Groundwater Hydraulics and Well Performance
2. Pump Types, Components, and Selection
3. Electrical Systems and Motor Controls
4. Plumbing, Piping, and Valves
5. Safety Practices and PPE
6. Regulations, Codes, and Legal Compliance
7. Troubleshooting, Diagnostics, and Repair
8. Water Quality, Treatment, and Contamination Prevention
*9. System Design, Installation, and Start-Up*
10. Ethics, Professional Conduct, and Customer Relations
Introduction
This assessment evaluates the knowledge and applied skills required for the NGWA Certified Pump Installer (CPI)
credential. Candidates will demonstrate mastery of groundwater hydraulics, pump selection, electrical systems,
safety protocols, regulatory compliance, troubleshooting, and professional ethics. Questions are multiple-choice
and scenario-based, emphasizing real-world decision-making during installation, diagnosis, and repair. Each
question includes a verified correct answer and a clear rationale. Success requires both theoretical understanding
and practical field judgment.
SECTION ONE: QUESTIONS 1–100
,1. A submersible pump is selected for a 6-inch diameter well with a static water level of 80 feet and a pumping
level of 150 feet. What is the minimum recommended pump housing diameter?
A. 4.5 inches
B. 5.0 inches
C. 5.5 inches
D. 3.9 inches
🟢D
🔴 RATIONALE: Pump housing must allow adequate annular space for cooling and sand settling; in a 6-inch
well, maximum pump diameter is 4.9 inches, so 3.9 inches is correct and safe.
2. A constant pressure system using a variable frequency drive (VFD) fails to maintain setpoint pressure under
varying flow. What is the most likely cause?
A. Pressure transducer is calibrated correctly
B. Motor nameplate horsepower exceeds drive rating
C. Drive is in hand mode instead of auto
D. Discharge check valve is fully open
🟢C
🔴 RATIONALE: Hand mode locks drive at fixed speed; auto mode allows VFD to adjust frequency based on
feedback from transducer to maintain pressure.
3. According to the National Electrical Code (NEC), what is the minimum burial depth for rigid metal conduit
(RMC) supplying a pump in a residential yard?
A. 6 inches
B. 12 inches
,C. 18 inches
D. 24 inches
🟢A
🔴 RATIONALE: NEC Table 300.5 allows RMC burial at 6 inches for residential locations; other conduits require
deeper depths.
4. A centrifugal pump operating against a closed discharge valve will experience:
A. Maximum flow and minimum power
B. Minimum flow and maximum temperature rise
C. Maximum efficiency and minimum pressure
D. Cavitation and vibration only
🟢B
🔴 RATIONALE: Closed valve = zero flow; recirculation heats water rapidly, causing potential pump damage if
prolonged.
5. You arrive at a site where the pump runs continuously but delivers very little water. Pressure gauge at the
tank reads 20 psi while pump is running. The most likely cause is:
A. Worn impeller or severe internal wear
B. Air-locked drop pipe
C. Closed gate valve after the tank
D. Oversized pressure switch differential
🟢A
🔴 RATIONALE: Low flow with running pump and low pressure typically indicates impeller wear, failed diffuser,
or severe internal recirculation.
, 6. Which of the following is the most appropriate first action when a pump installer discovers an unlabeled wire
in a control box?
A. Cap it and ignore
B. Apply voltage and test with a multimeter
C. Trace continuity back to source
D. Connect it to ground
🟢C
🔴 RATIONALE: Safety requires identifying unknown wires by continuity tracing before energizing to prevent
short circuits or electrocution.
7. A customer reports rusty water only after the pump shuts off. The well is 10 years old. What is the most
probable cause?
A. Galvanized drop pipe corrosion
B. Sand pumping from aquifer
C. Failure of bladder tank
D. Low water table
🟢A
🔴 RATIONALE: Rust after pump off indicates corrosion products settling; galvanized steel drop pipe commonly
fails this way, especially in aggressive water.
8. When lowering a submersible pump into a drilled well, the torque arrestor should be placed:
A. Directly above the pump motor
B. At the well seal
C. Midway up the drop pipe
D. Every 20 feet
