Class D Water Exam Illinois Questions &
Answers
For a water storage tank, cathodic protection is only effective for the: - ANSWERStank
areas covered by water
For a water storage system, the purpose of an altitude valve is to prevent: -
ANSWERSoverflows
Before using a water storage tank that has been disinfected, water from the tank must
not show the presense of: - ANSWERScoliforms
High trihalomethane (THMs) levels may cause: - ANSWERScancer
A finished water with a negative Langelier Index may be: - ANSWERScorrosive
Water with pH scale less than 7 is considered: - ANSWERSacidic
pH scale of 7 is considered - ANSWERSneutral
pH scale of 8-14 is considered? - ANSWERSbasic
How many gallons of water are in 1 cubic ft? - ANSWERS7.48 gallons
How many gallons of water are in 15 cubic ft? - ANSWERS15 x 7.48 = 112.2 gallons
How many cubic ft of water is 20 gallons? - ANSWERS20/7.48 = 2.67 cubic ft
1 gallon of water equals how many lbs? - ANSWERS8.34 lbs
16 gallons of water is how many lbs? - ANSWERS16 x 8.34 = 133.44 lbs
, A 180 ft water tower would show what psi on the gauge located at the base? -
ANSWERS180/ 2.31 = 77.92 psi
Pump cavitation is most likely to occur when: - ANSWERSthe top of the water source
level is lower than the impeller
1 pound per square inch is equal to how many feet of elevated water? - ANSWERS2.31
feet
For most centrifugal pumps, if the total dyanmic head decreases, the pump will: -
ANSWERSpump water at a faster rate in gpm. (less head to push against)
The velocity of water is measure in: - ANSWERSFeet per Second
Distance (feet)/Time (sec)
When water lines in a distribution system are installed parallel to sewer lines, they
should be located how far apart from the sewer lines? - ANSWERS10 ft
Air relief valves in the distribution system should be located where? - ANSWERSat the
high point on a main
What is the minimum psi that needs to be continually maintained in all parts of a water
distribution system? - ANSWERS20 psi
What could occur if the minimum distribution system pressure is not maintained? -
ANSWERSbacksiphonage
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? -
ANSWERS2,447 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
The IEPA requires that routine bacteria samples be taken and analyzed how often? -
ANSWERSEvery month
When taking a bacteria sample, the sample bottle should be filled with water: -
ANSWERSto the 100mL line
While taking a bacteria water sample, what should also be done at the same time and
location? - ANSWERSchlorine residual test
Answers
For a water storage tank, cathodic protection is only effective for the: - ANSWERStank
areas covered by water
For a water storage system, the purpose of an altitude valve is to prevent: -
ANSWERSoverflows
Before using a water storage tank that has been disinfected, water from the tank must
not show the presense of: - ANSWERScoliforms
High trihalomethane (THMs) levels may cause: - ANSWERScancer
A finished water with a negative Langelier Index may be: - ANSWERScorrosive
Water with pH scale less than 7 is considered: - ANSWERSacidic
pH scale of 7 is considered - ANSWERSneutral
pH scale of 8-14 is considered? - ANSWERSbasic
How many gallons of water are in 1 cubic ft? - ANSWERS7.48 gallons
How many gallons of water are in 15 cubic ft? - ANSWERS15 x 7.48 = 112.2 gallons
How many cubic ft of water is 20 gallons? - ANSWERS20/7.48 = 2.67 cubic ft
1 gallon of water equals how many lbs? - ANSWERS8.34 lbs
16 gallons of water is how many lbs? - ANSWERS16 x 8.34 = 133.44 lbs
, A 180 ft water tower would show what psi on the gauge located at the base? -
ANSWERS180/ 2.31 = 77.92 psi
Pump cavitation is most likely to occur when: - ANSWERSthe top of the water source
level is lower than the impeller
1 pound per square inch is equal to how many feet of elevated water? - ANSWERS2.31
feet
For most centrifugal pumps, if the total dyanmic head decreases, the pump will: -
ANSWERSpump water at a faster rate in gpm. (less head to push against)
The velocity of water is measure in: - ANSWERSFeet per Second
Distance (feet)/Time (sec)
When water lines in a distribution system are installed parallel to sewer lines, they
should be located how far apart from the sewer lines? - ANSWERS10 ft
Air relief valves in the distribution system should be located where? - ANSWERSat the
high point on a main
What is the minimum psi that needs to be continually maintained in all parts of a water
distribution system? - ANSWERS20 psi
What could occur if the minimum distribution system pressure is not maintained? -
ANSWERSbacksiphonage
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? -
ANSWERS2,447 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
The IEPA requires that routine bacteria samples be taken and analyzed how often? -
ANSWERSEvery month
When taking a bacteria sample, the sample bottle should be filled with water: -
ANSWERSto the 100mL line
While taking a bacteria water sample, what should also be done at the same time and
location? - ANSWERSchlorine residual test
