NGWA Water Systems Certification
Exam (Less Than 100 GPM – Exam K) –
Practice Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. What is the primary purpose of a water system serving less than 100
GPM?
A. Industrial cooling
B. Fire suppression
C. Domestic water supply
D. Irrigation
Rationale: Domestic water supply is the main purpose for small-
capacity water systems.
2. What is the recommended minimum separation between a well and a
septic system?
, A. 25 feet
B. 50 feet
C. 100 feet
D. 150 feet
Rationale: 100 feet is the standard minimum to prevent
contamination from septic systems.
3. Which type of pump is most commonly used in small water systems?
A. Centrifugal
B. Submersible
C. Gear
D. Screw
Rationale: Submersible pumps are efficient for small well systems
and minimize priming issues.
4. What is the primary reason to install a pressure tank in a water
system?
A. Increase water temperature
B. Maintain system pressure and reduce pump cycling
C. Filter water
D. Add chemicals
Rationale: Pressure tanks help maintain consistent pressure and
extend pump life.
5. What is the typical maximum pumping rate for a small residential
well?
, A. 50 GPM
B. 100 GPM
C. 200 GPM
D. 500 GPM
Rationale: The exam focuses on systems less than 100 GPM, which is
typical for residential supply.
6. What is the primary cause of pump cavitation?
A. Excess pressure
B. Low voltage
C. Insufficient inlet pressure
D. High water temperature
Rationale: Cavitation occurs when the pump’s inlet pressure is too
low, causing vapor bubbles.
7. Which component prevents backflow into a well?
A. Check valve
B. Gate valve
C. Foot valve
D. Pressure switch
Rationale: A foot valve at the pump intake prevents water from
flowing backward.
8. What is the recommended depth for frost protection of a water line in
most climates?
A. 12 inches
, B. 24 inches
C. 36 inches
D. Below local frost line
Rationale: Installing lines below the frost line prevents freezing in
winter.
9. What type of water system is most likely to require regular
disinfection?
A. Municipal
B. Private wells
C. Large irrigation systems
D. Fire suppression systems
Rationale: Private wells can be vulnerable to contamination and
often need periodic disinfection.
10. Which type of material is commonly used for small water system
piping?
A. Cast iron
B. Copper
C. PVC or polyethylene
D. Galvanized steel
Rationale: PVC and polyethylene are cost-effective, durable, and safe
for potable water.
11. How often should water quality testing be conducted in small
residential systems?
Exam (Less Than 100 GPM – Exam K) –
Practice Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. What is the primary purpose of a water system serving less than 100
GPM?
A. Industrial cooling
B. Fire suppression
C. Domestic water supply
D. Irrigation
Rationale: Domestic water supply is the main purpose for small-
capacity water systems.
2. What is the recommended minimum separation between a well and a
septic system?
, A. 25 feet
B. 50 feet
C. 100 feet
D. 150 feet
Rationale: 100 feet is the standard minimum to prevent
contamination from septic systems.
3. Which type of pump is most commonly used in small water systems?
A. Centrifugal
B. Submersible
C. Gear
D. Screw
Rationale: Submersible pumps are efficient for small well systems
and minimize priming issues.
4. What is the primary reason to install a pressure tank in a water
system?
A. Increase water temperature
B. Maintain system pressure and reduce pump cycling
C. Filter water
D. Add chemicals
Rationale: Pressure tanks help maintain consistent pressure and
extend pump life.
5. What is the typical maximum pumping rate for a small residential
well?
, A. 50 GPM
B. 100 GPM
C. 200 GPM
D. 500 GPM
Rationale: The exam focuses on systems less than 100 GPM, which is
typical for residential supply.
6. What is the primary cause of pump cavitation?
A. Excess pressure
B. Low voltage
C. Insufficient inlet pressure
D. High water temperature
Rationale: Cavitation occurs when the pump’s inlet pressure is too
low, causing vapor bubbles.
7. Which component prevents backflow into a well?
A. Check valve
B. Gate valve
C. Foot valve
D. Pressure switch
Rationale: A foot valve at the pump intake prevents water from
flowing backward.
8. What is the recommended depth for frost protection of a water line in
most climates?
A. 12 inches
, B. 24 inches
C. 36 inches
D. Below local frost line
Rationale: Installing lines below the frost line prevents freezing in
winter.
9. What type of water system is most likely to require regular
disinfection?
A. Municipal
B. Private wells
C. Large irrigation systems
D. Fire suppression systems
Rationale: Private wells can be vulnerable to contamination and
often need periodic disinfection.
10. Which type of material is commonly used for small water system
piping?
A. Cast iron
B. Copper
C. PVC or polyethylene
D. Galvanized steel
Rationale: PVC and polyethylene are cost-effective, durable, and safe
for potable water.
11. How often should water quality testing be conducted in small
residential systems?
