Class D Water Exam Illinois Latest Update 2025-
2026 Exam 115 Questions with 100% Verified
Correct Answers Guaranteed A+
1 gallon of water equals how many lbs? - CORRECT ANSWER: 8.34 lbs
1 pound per square inch is equal to how many feet of elevated water? - CORRECT
ANSWER: 2.31 feet
16 gallons of water is how many lbs? - CORRECT ANSWER: 16 x 8.34 = 133.44 lbs
A 180 ft water tower would show what psi on the gauge located at the base? -
CORRECT ANSWER: 180/ 2.31 = 77.92 psi
A bacteria water sample must be mailed so that the labe analysis can begin no later
than: - CORRECT ANSWER: 30 hours after the sample was collected
A boil order should be issued whenever the following type of water contamination is
suspected: - CORRECT ANSWER: Bacteria contamination
A compound meter inlcludes: - CORRECT ANSWER: a turbine and positive
displacement meter
Turbine = High flow
Positive displacement = low flow
A dry chemical that is 65% available chlorine is being used to provide a 50 mg/l
disinfection dosage to a completely full 95,000 gallon water storage tank. Approximately
how many pounds of chemical are need? - CORRECT ANSWER: 61 lbs dry chemical
, use pounds formula
95,000= 0.095 MG
A finished water with a negative Langelier Index may be: - CORRECT ANSWER:
corrosive
A fure or circuit breaker is used to: - CORRECT ANSWER: protect a pump/motor
A ground storage tank is 50 feet in diameter and 30 feet high. If the tank is being filled at
a 10 feet rise in level per hour, how many gallons per minute are flowing into the tank? -
CORRECT ANSWER: 2,447 gpm
(Ignore the heighth)
.785 X 50ft x 50ft x (10ft/1hr) = 19,625 cubic ft/1hr
1 cubic ft = 7.48 gallons
(19,625 cubic ft/1hr) x (7.48 gal/1 cubic ft) = 146,795 gal per HR
60 mins = 1 HR
146,795/60= 2,446.58 GPM
A Langelier Index of 0 (zero) means the finished water is: - CORRECT ANSWER: stable
A lantern ring would be located in the: - CORRECT ANSWER: stuffing box
A negative Langelier Index means the finished water is: - CORRECT ANSWER:
corrosive
A positive Langelier Index can be produced by adding: - CORRECT ANSWER: caustic
soda
(Sodium Hydroxide NaOH)
2026 Exam 115 Questions with 100% Verified
Correct Answers Guaranteed A+
1 gallon of water equals how many lbs? - CORRECT ANSWER: 8.34 lbs
1 pound per square inch is equal to how many feet of elevated water? - CORRECT
ANSWER: 2.31 feet
16 gallons of water is how many lbs? - CORRECT ANSWER: 16 x 8.34 = 133.44 lbs
A 180 ft water tower would show what psi on the gauge located at the base? -
CORRECT ANSWER: 180/ 2.31 = 77.92 psi
A bacteria water sample must be mailed so that the labe analysis can begin no later
than: - CORRECT ANSWER: 30 hours after the sample was collected
A boil order should be issued whenever the following type of water contamination is
suspected: - CORRECT ANSWER: Bacteria contamination
A compound meter inlcludes: - CORRECT ANSWER: a turbine and positive
displacement meter
Turbine = High flow
Positive displacement = low flow
A dry chemical that is 65% available chlorine is being used to provide a 50 mg/l
disinfection dosage to a completely full 95,000 gallon water storage tank. Approximately
how many pounds of chemical are need? - CORRECT ANSWER: 61 lbs dry chemical
, use pounds formula
95,000= 0.095 MG
A finished water with a negative Langelier Index may be: - CORRECT ANSWER:
corrosive
A fure or circuit breaker is used to: - CORRECT ANSWER: protect a pump/motor
A ground storage tank is 50 feet in diameter and 30 feet high. If the tank is being filled at
a 10 feet rise in level per hour, how many gallons per minute are flowing into the tank? -
CORRECT ANSWER: 2,447 gpm
(Ignore the heighth)
.785 X 50ft x 50ft x (10ft/1hr) = 19,625 cubic ft/1hr
1 cubic ft = 7.48 gallons
(19,625 cubic ft/1hr) x (7.48 gal/1 cubic ft) = 146,795 gal per HR
60 mins = 1 HR
146,795/60= 2,446.58 GPM
A Langelier Index of 0 (zero) means the finished water is: - CORRECT ANSWER: stable
A lantern ring would be located in the: - CORRECT ANSWER: stuffing box
A negative Langelier Index means the finished water is: - CORRECT ANSWER:
corrosive
A positive Langelier Index can be produced by adding: - CORRECT ANSWER: caustic
soda
(Sodium Hydroxide NaOH)
