PHIUS CLASS D WATER EXAM WITH ALL CORRECT &
VERIFIED ANSWERS (UPDATED TO PASS)
For a water storage tank, cathodic protection is only effective for the: Correct answer-tank areas
covered by water
For a water storage system, the purpose of an altitude valve is to prevent: Correct answer-
overflows
Before using a water storage tank that has been disinfected, water from the tank must not show the
presense of: Correct answer-coliforms
High trihalomethane (THMs) levels may cause: Correct answer-cancer
A finished water with a negative Langelier Index may be: Correct answer-corrosive
Water with pH scale less than 7 is considered: Correct answer-acidic
pH scale of 7 is considered Correct answer-neutral
pH scale of 8-14 is considered? Correct answer-basic
How many gallons of water are in 1 cubic ft? Correct answer-7.48 gallons
How many gallons of water are in 15 cubic ft? Correct answer-15 x 7.48 = 112.2 gallons
How many cubic ft of water is 20 gallons? Correct answer-20/7.48 = 2.67 cubic ft
1 gallon of water equals how many lbs? Correct answer-8.34 lbs
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
Pump cavitation is most likely to occur when: Correct answer-the 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? Correct answer-2.31 feet
For most centrifugal pumps, if the total dyanmic head decreases, the pump will: Correct answer-
pump water at a faster rate in gpm. (less head to push against)
The velocity of water is measure in: Correct answer-Feet 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? Correct answer-10 ft
, Air relief valves in the distribution system should be located where? Correct answer-at 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? Correct answer-20 psi
What could occur if the minimum distribution system pressure is not maintained? Correct answer-
backsiphonage
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
The IEPA requires that routine bacteria samples be taken and analyzed how often? Correct answer-
Every month
When taking a bacteria sample, the sample bottle should be filled with water: Correct answer-to
the 100mL line
While taking a bacteria water sample, what should also be done at the same time and location?
Correct answer-chlorine residual test
What is a chlorine residual and what does it show? Correct answer-The actual amount of chlorine
remaining in the water to act as a disinfectant. Indicates that a sufficient amount of chlorine was
added to the water to inactivate bacteria and some viruses.
If coliform bacteria are found in a water sample. This indicates that: Correct answer-repeat
samples should be taken. human or animal feces are present.
Sodium thiosulfate is added to Bac-T sampling bottles in order to: Correct answer-neutralize any
chlorine in the sample
For bacteria contamination, if repeat samples are required, they should be taken: Correct answer-
within 24 hours
Which backflow preventer is most likely to be installed as part of a water service line for a single
family home? Correct answer-dual check
If practical, water mains should be how far above sewer lines? Correct answer-18 inches
Which water meter is most likely to be used for a single family home? Correct answer-
Displacement meter
Older water meters for a single family home are most likely to? Correct answer-under register
VERIFIED ANSWERS (UPDATED TO PASS)
For a water storage tank, cathodic protection is only effective for the: Correct answer-tank areas
covered by water
For a water storage system, the purpose of an altitude valve is to prevent: Correct answer-
overflows
Before using a water storage tank that has been disinfected, water from the tank must not show the
presense of: Correct answer-coliforms
High trihalomethane (THMs) levels may cause: Correct answer-cancer
A finished water with a negative Langelier Index may be: Correct answer-corrosive
Water with pH scale less than 7 is considered: Correct answer-acidic
pH scale of 7 is considered Correct answer-neutral
pH scale of 8-14 is considered? Correct answer-basic
How many gallons of water are in 1 cubic ft? Correct answer-7.48 gallons
How many gallons of water are in 15 cubic ft? Correct answer-15 x 7.48 = 112.2 gallons
How many cubic ft of water is 20 gallons? Correct answer-20/7.48 = 2.67 cubic ft
1 gallon of water equals how many lbs? Correct answer-8.34 lbs
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
Pump cavitation is most likely to occur when: Correct answer-the 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? Correct answer-2.31 feet
For most centrifugal pumps, if the total dyanmic head decreases, the pump will: Correct answer-
pump water at a faster rate in gpm. (less head to push against)
The velocity of water is measure in: Correct answer-Feet 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? Correct answer-10 ft
, Air relief valves in the distribution system should be located where? Correct answer-at 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? Correct answer-20 psi
What could occur if the minimum distribution system pressure is not maintained? Correct answer-
backsiphonage
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
The IEPA requires that routine bacteria samples be taken and analyzed how often? Correct answer-
Every month
When taking a bacteria sample, the sample bottle should be filled with water: Correct answer-to
the 100mL line
While taking a bacteria water sample, what should also be done at the same time and location?
Correct answer-chlorine residual test
What is a chlorine residual and what does it show? Correct answer-The actual amount of chlorine
remaining in the water to act as a disinfectant. Indicates that a sufficient amount of chlorine was
added to the water to inactivate bacteria and some viruses.
If coliform bacteria are found in a water sample. This indicates that: Correct answer-repeat
samples should be taken. human or animal feces are present.
Sodium thiosulfate is added to Bac-T sampling bottles in order to: Correct answer-neutralize any
chlorine in the sample
For bacteria contamination, if repeat samples are required, they should be taken: Correct answer-
within 24 hours
Which backflow preventer is most likely to be installed as part of a water service line for a single
family home? Correct answer-dual check
If practical, water mains should be how far above sewer lines? Correct answer-18 inches
Which water meter is most likely to be used for a single family home? Correct answer-
Displacement meter
Older water meters for a single family home are most likely to? Correct answer-under register
