Page 1 of 135
Virginia Waterworks Operator Class 5 Exam Questions
with Correct Answers and explanations LATEST THIS
YEAR -JUST RELEASED
Virginia Waterworks Operator Class 5 Exam
Exam Coverage Summary
The Virginia Waterworks Operator Class 5 exam is designed for operators of small to medium-sized
water treatment and distribution systems. According to Virginia Administrative Code 18VAC160-30-110,
candidates must have a high school diploma or GED (or equivalent experience) and meet specific
experience requirements .
Key exam topics include:
• Disinfection and Chlorination: Breakpoint chlorination, free vs. combined chlorine,
hypochlorination, DPD testing
• Distribution System Operations: Backflow prevention devices (air gap, RPZ, DCVA), pressure
regulation, flushing, corrosion control, booster pumps
• Water Quality Parameters: pH, alkalinity, turbidity, iron and manganese control (sequestration),
hardness
• Regulatory Compliance: Lead and Copper Rule, Consumer Confidence Reports (CCRs), Maximum
Contaminant Levels (MCLs)
• Wellhead Protection: Sanitary seals, contamination prevention
• Safety: Confined space entry, Lockout/Tagout (LOTO), PPE for chemical handling
• Sampling and Testing: Bacteriological sampling techniques, chain of custody, instrument use
(turbidimeter, pH meter, colorimeter)
• Storage Tanks: Detention time, turnover, water quality maintenance
Question 1
What is the primary purpose of a sanitary seal on a wellhead?
A) To increase water pressure from the well pump
B) To prevent surface contamination, insects, and debris from entering the well
C) To improve the efficiency of the submersible pump
D) To reduce the temperature of the groundwater
Correct Answer: B
Summary Rationale: A sanitary seal blocks surface water, insects, and debris from entering the well,
protecting raw water quality at the source .
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Question 2
In a Class 5 water system, which form of chlorine is most commonly used for hypochlorination?
A) Chlorine gas
B) Calcium hypochlorite
C) Ozone
D) Ultraviolet light
Correct Answer: B
Summary Rationale: Calcium hypochlorite is a solid, stable source of free chlorine suitable for small
systems, making it the most common choice for hypochlorination .
Question 3
What does the term "free chlorine" refer to in water treatment?
A) Chlorine bound to organic matter or ammonia
B) Uncombined chlorine available for disinfection
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C) The total chlorine present in the water sample
D) Chlorine in the form of chloramines
Correct Answer: B
Summary Rationale: Free chlorine is the portion of chlorine not combined with ammonia or organic
compounds; it is the active disinfectant that kills pathogens .
Question 4
Which of the following best describes "breakpoint chlorination"?
A) Adding chlorine until the water turns a deep green color
B) Adding chlorine until all ammonia is oxidized and free chlorine residual begins to rise
C) Adding chlorine until the pH drops below 6.5
D) Adding chlorine until turbidity reaches zero
Correct Answer: B
Summary Rationale: Breakpoint chlorination occurs when enough chlorine has been added to oxidize all
ammonia, after which a free chlorine residual appears .
, Page 4 of 135
Question 5
What is the primary function of a calcite contactor in water treatment?
A) To remove iron and manganese
B) To increase water hardness
C) To raise pH and provide corrosion control
D) To disinfect the water supply
Correct Answer: C
Summary Rationale: Calcite (calcium carbonate) dissolves in water, raising pH and creating a protective
calcium carbonate film inside pipes for corrosion control .
Question 6
What is the most common cause of backpressure backflow in a distribution system?
A) A sudden drop in the municipal water pressure
B) A higher pressure in the customer's line than in the supply main
Virginia Waterworks Operator Class 5 Exam Questions
with Correct Answers and explanations LATEST THIS
YEAR -JUST RELEASED
Virginia Waterworks Operator Class 5 Exam
Exam Coverage Summary
The Virginia Waterworks Operator Class 5 exam is designed for operators of small to medium-sized
water treatment and distribution systems. According to Virginia Administrative Code 18VAC160-30-110,
candidates must have a high school diploma or GED (or equivalent experience) and meet specific
experience requirements .
Key exam topics include:
• Disinfection and Chlorination: Breakpoint chlorination, free vs. combined chlorine,
hypochlorination, DPD testing
• Distribution System Operations: Backflow prevention devices (air gap, RPZ, DCVA), pressure
regulation, flushing, corrosion control, booster pumps
• Water Quality Parameters: pH, alkalinity, turbidity, iron and manganese control (sequestration),
hardness
• Regulatory Compliance: Lead and Copper Rule, Consumer Confidence Reports (CCRs), Maximum
Contaminant Levels (MCLs)
• Wellhead Protection: Sanitary seals, contamination prevention
• Safety: Confined space entry, Lockout/Tagout (LOTO), PPE for chemical handling
• Sampling and Testing: Bacteriological sampling techniques, chain of custody, instrument use
(turbidimeter, pH meter, colorimeter)
• Storage Tanks: Detention time, turnover, water quality maintenance
Question 1
What is the primary purpose of a sanitary seal on a wellhead?
A) To increase water pressure from the well pump
B) To prevent surface contamination, insects, and debris from entering the well
C) To improve the efficiency of the submersible pump
D) To reduce the temperature of the groundwater
Correct Answer: B
Summary Rationale: A sanitary seal blocks surface water, insects, and debris from entering the well,
protecting raw water quality at the source .
, Page 2 of 135
Question 2
In a Class 5 water system, which form of chlorine is most commonly used for hypochlorination?
A) Chlorine gas
B) Calcium hypochlorite
C) Ozone
D) Ultraviolet light
Correct Answer: B
Summary Rationale: Calcium hypochlorite is a solid, stable source of free chlorine suitable for small
systems, making it the most common choice for hypochlorination .
Question 3
What does the term "free chlorine" refer to in water treatment?
A) Chlorine bound to organic matter or ammonia
B) Uncombined chlorine available for disinfection
, Page 3 of 135
C) The total chlorine present in the water sample
D) Chlorine in the form of chloramines
Correct Answer: B
Summary Rationale: Free chlorine is the portion of chlorine not combined with ammonia or organic
compounds; it is the active disinfectant that kills pathogens .
Question 4
Which of the following best describes "breakpoint chlorination"?
A) Adding chlorine until the water turns a deep green color
B) Adding chlorine until all ammonia is oxidized and free chlorine residual begins to rise
C) Adding chlorine until the pH drops below 6.5
D) Adding chlorine until turbidity reaches zero
Correct Answer: B
Summary Rationale: Breakpoint chlorination occurs when enough chlorine has been added to oxidize all
ammonia, after which a free chlorine residual appears .
, Page 4 of 135
Question 5
What is the primary function of a calcite contactor in water treatment?
A) To remove iron and manganese
B) To increase water hardness
C) To raise pH and provide corrosion control
D) To disinfect the water supply
Correct Answer: C
Summary Rationale: Calcite (calcium carbonate) dissolves in water, raising pH and creating a protective
calcium carbonate film inside pipes for corrosion control .
Question 6
What is the most common cause of backpressure backflow in a distribution system?
A) A sudden drop in the municipal water pressure
B) A higher pressure in the customer's line than in the supply main
