Page 1 of 129
Florida Class C Water Treatment Operator Questions
with Correct Answers and explanations LATEST THIS
YEAR -JUST RELEASED
Summarized Exam Coverage – Florida Class C Water Treatment Operator
The Florida Class C Water Treatment Operator exam (administered by FDEP) covers water treatment
processes (coagulation, flocculation, sedimentation, filtration, disinfection with chlorine, chloramines,
UV, ozone), distribution system operations (pumping, storage, flushing, pressure management), water
quality parameters (turbidity, pH, alkalinity, hardness, chlorine residual, coliform bacteria, lead/copper,
disinfection byproducts), regulations (Safe Drinking Water Act, Florida Administrative Code 62-550,
62-555, 62-602 requirements for Class C licensure: high school diploma, 1 year/2,080 hours of qualifying
experience, passing exam grade valid for 4 years), safety (confined space, lockout/tagout, chlorine
safety, PPE, emergency response), instrumentation and control (flow meters, level sensors, SCADA
basics), maintenance (pumps, valves, motors, chemical feed systems), laboratory procedures (sampling,
testing for pH, turbidity, chlorine, alkalinity), water math (detention time, flow rates, chemical dosages,
volume calculations, chlorine demand, percent strength, loading rates). Exam eligibility: complete a
FDEP-approved training course, pass the exam, document experience, and apply for license.
1. A water treatment plant operator calculates that the clearwell has a volume of 100,000 gallons and
the plant flow rate is 500 gallons per minute. What is the detention time in minutes?
A) 50 minutes
B) 100 minutes
C) 200 minutes
D) 400 minutes
*Answer: C — Detention time = volume ÷ flow rate = 100,000 ÷ 500 = 200 minutes.*
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2. An operator observes that the turbidity of settled water before filtration has increased from 1.2 NTU
to 3.5 NTU. What process control adjustment should be made first?
A) Increase the filtration rate
B) Increase the coagulant dosage or check coagulation/flocculation efficiency
C) Backwash the filters immediately
D) Decrease the chlorine dosage
Answer: B — High settled water turbidity indicates poor coagulation or flocculation; adjusting coagulant
or mixing is the appropriate first step.
3. A water sample tests positive for total coliform bacteria. Under Florida rules (Chapter 62-550), what is
the required action for a public water system?
A) No action unless E. coli is also present
B) Repeat sampling within 24 hours and notify FDEP
C) Wait for the next routine sample
D) Increase chlorine by 5 mg/L without testing
Answer: B — Any total coliform-positive routine sample requires repeat samples within 24 hours and
notification to the regulatory agency.
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4. An operator must add 5 mg/L of chlorine to a flow of 2 million gallons per day (MGD). How many
pounds of chlorine are needed per day? (Assume 1 gal water = 8.34 lb)
A) 8.34 lb
B) 41.7 lb
C) 83.4 lb
D) 167 lb
*Answer: C — lbs/day = flow (MGD) × dose (mg/L) × 8.34 = 2 × 5 × 8.34 = 83.4 lbs.*
5. A storage tank has a diameter of 50 feet and a water depth of 20 feet. What is the approximate
volume in gallons? (1 ft³ = 7.48 gal)
A) 39,250 gallons
B) 78,500 gallons
C) 293,000 gallons
D) 587,000 gallons
*Answer: C — Area = π × r² = 3.14 × (25)² = 1,962.5 ft²; volume = 1,962.5 × 20 = 39,250 ft³ × 7.48 =
~293,000 gallons.*
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6. A water treatment plant uses chlorine gas for disinfection. The chlorine room has a leak detector that
alarms. What is the operator’s first priority?
A) Call the supervisor
B) Evacuate the area and put on a self-contained breathing apparatus (SCBA) before attempting to
locate the leak
C) Turn off the ventilation fan
D) Close the chlorine cylinder valve without any PPE
Answer: B — Chlorine gas is highly toxic; protecting oneself with SCBA is the first priority before any
corrective action.
7. An operator must calculate the chemical feed pump setting for a polymer solution. The desired dose
is 0.5 mg/L, the plant flow is 3 MGD, and the polymer solution strength is 5%. What is the required feed
rate in gallons per day? (Assume 1 gal solution weighs 8.34 lb)
A) 6 gal/day
B) 30 gal/day
C) 60 gal/day
D) 300 gal/day
Florida Class C Water Treatment Operator Questions
with Correct Answers and explanations LATEST THIS
YEAR -JUST RELEASED
Summarized Exam Coverage – Florida Class C Water Treatment Operator
The Florida Class C Water Treatment Operator exam (administered by FDEP) covers water treatment
processes (coagulation, flocculation, sedimentation, filtration, disinfection with chlorine, chloramines,
UV, ozone), distribution system operations (pumping, storage, flushing, pressure management), water
quality parameters (turbidity, pH, alkalinity, hardness, chlorine residual, coliform bacteria, lead/copper,
disinfection byproducts), regulations (Safe Drinking Water Act, Florida Administrative Code 62-550,
62-555, 62-602 requirements for Class C licensure: high school diploma, 1 year/2,080 hours of qualifying
experience, passing exam grade valid for 4 years), safety (confined space, lockout/tagout, chlorine
safety, PPE, emergency response), instrumentation and control (flow meters, level sensors, SCADA
basics), maintenance (pumps, valves, motors, chemical feed systems), laboratory procedures (sampling,
testing for pH, turbidity, chlorine, alkalinity), water math (detention time, flow rates, chemical dosages,
volume calculations, chlorine demand, percent strength, loading rates). Exam eligibility: complete a
FDEP-approved training course, pass the exam, document experience, and apply for license.
1. A water treatment plant operator calculates that the clearwell has a volume of 100,000 gallons and
the plant flow rate is 500 gallons per minute. What is the detention time in minutes?
A) 50 minutes
B) 100 minutes
C) 200 minutes
D) 400 minutes
*Answer: C — Detention time = volume ÷ flow rate = 100,000 ÷ 500 = 200 minutes.*
, Page 2 of 129
2. An operator observes that the turbidity of settled water before filtration has increased from 1.2 NTU
to 3.5 NTU. What process control adjustment should be made first?
A) Increase the filtration rate
B) Increase the coagulant dosage or check coagulation/flocculation efficiency
C) Backwash the filters immediately
D) Decrease the chlorine dosage
Answer: B — High settled water turbidity indicates poor coagulation or flocculation; adjusting coagulant
or mixing is the appropriate first step.
3. A water sample tests positive for total coliform bacteria. Under Florida rules (Chapter 62-550), what is
the required action for a public water system?
A) No action unless E. coli is also present
B) Repeat sampling within 24 hours and notify FDEP
C) Wait for the next routine sample
D) Increase chlorine by 5 mg/L without testing
Answer: B — Any total coliform-positive routine sample requires repeat samples within 24 hours and
notification to the regulatory agency.
, Page 3 of 129
4. An operator must add 5 mg/L of chlorine to a flow of 2 million gallons per day (MGD). How many
pounds of chlorine are needed per day? (Assume 1 gal water = 8.34 lb)
A) 8.34 lb
B) 41.7 lb
C) 83.4 lb
D) 167 lb
*Answer: C — lbs/day = flow (MGD) × dose (mg/L) × 8.34 = 2 × 5 × 8.34 = 83.4 lbs.*
5. A storage tank has a diameter of 50 feet and a water depth of 20 feet. What is the approximate
volume in gallons? (1 ft³ = 7.48 gal)
A) 39,250 gallons
B) 78,500 gallons
C) 293,000 gallons
D) 587,000 gallons
*Answer: C — Area = π × r² = 3.14 × (25)² = 1,962.5 ft²; volume = 1,962.5 × 20 = 39,250 ft³ × 7.48 =
~293,000 gallons.*
, Page 4 of 129
6. A water treatment plant uses chlorine gas for disinfection. The chlorine room has a leak detector that
alarms. What is the operator’s first priority?
A) Call the supervisor
B) Evacuate the area and put on a self-contained breathing apparatus (SCBA) before attempting to
locate the leak
C) Turn off the ventilation fan
D) Close the chlorine cylinder valve without any PPE
Answer: B — Chlorine gas is highly toxic; protecting oneself with SCBA is the first priority before any
corrective action.
7. An operator must calculate the chemical feed pump setting for a polymer solution. The desired dose
is 0.5 mg/L, the plant flow is 3 MGD, and the polymer solution strength is 5%. What is the required feed
rate in gallons per day? (Assume 1 gal solution weighs 8.34 lb)
A) 6 gal/day
B) 30 gal/day
C) 60 gal/day
D) 300 gal/day
