WATER DISTRIBUTION FINAL EXAM QUESTIONS
WITH CORRECT ANSWERS 2025/2026
Delivered min. Working pressure - correct answer -35 psi
Rp backflow preventer will stop... - correct answer -back pressure and back siphon age
Gate valves have less... - correct answer -friction loss
Cavitation is caused by... - correct answer -excess pump speed
Hydrant flow - correct answer -(2.83)(d^2)(l)/(square root of h)=gpm
Min. Distribution pressure - correct answer -20 psi
Aquifer - correct answer -water bearing stratum of rock, sand, or gravel
Type of rupture or breakage that may occur when a pipe is unevenly supported along its length -
correct answer -beam breakage
Awwa's max distance between residential valves - correct answer -800 ft.
Min. Flushing velocity when unidirectional flushing method - correct answer -5 fps
Which type of level sensor requires an air supply - correct answer -bubbler tube
Mcl for chloride - correct answer -250 mg/l
,Two tier 1 violations - correct answer -acute risk to health
Purpose for metallic tracer tape - correct answer -locating protection of distribution pipe
Min. Backflow protection against a cross connection containing a contaminant that is dangerous
to health - correct answer -double check valve assembly
Reverse water flow caused by a vacuum is called... - correct answer -back siphon age
Min. Contact time when disinfecting water mains with the chlorine slug method - correct
answer -3 hours
Di pipe primarily used for river crossings and underwater intakes - correct answer -ball and
socket
A reduced pressure zone device consists of two spring loaded check valves with a... - correct
answer -pressure regulated relief located between them
A venturi meter has... - correct answer -two taps, the downstream tap is the high pressure tap
Anodes suspended in a tank are used to prevent... - correct answer -corrosion
Min height of well vent pipe - correct answer -36 inches
Test that determines if mains need cleaning or replacement - correct answer -fire flow test
,Water demand in a community is usually estimated on the basis of - correct answer -per capita
demand
Valves needed at pipe crosses - correct answer -three
Valves needed at pipe tees - correct answer -two
Min acceptable cl2 residual when using chloramines for disinfection - correct answer -.6 mg/l
Cl2 residual needed to disinfect well casings - correct answer -50 ml/l
Backflows are installed downstream from the what - correct answer -meter
Double check backflows offer what level of protection - correct answer -least
Rp backflows offer what level of protection - correct answer -medium
Rp backflows have what between two check valves - correct answer -relief valve
What offers the highest level of backflow protection - correct answer -air gap
Min and max distance backflows to be off ground - correct answer -12 min 30 inches max
What is a more powerful disinfectant than chloramines - correct answer -chlorine
What disinfectant is more persistent than chlorine - correct answer -chloramines
, Chloramines are more effective than chlorine against what - correct answer -biofilms
Main chlorination at 25-50 mg/l is held for how long - correct answer -24 hours
Min cl2 residual for main after 24 hour hold - correct answer -10 mg/l
Main slug method at 100 mg/l must be held for min of - correct answer -3 hours
Calcium hypochlorite can support a fire when stored close to what - correct answer -organics
If cl2 residual leaving plant falls below .20, how long do you have to correct the problem -
correct answer -4 hours, if corrected under 4 hours not a violation, but regulatory agency must
be notified
Convert f to c - correct answer -(f-32)/1.8
Convert c to f - correct answer -(c x 1.8) + 32
How many times a day are cl2 residuals taken at small plants - correct answer -3 times a day
How often are cl2 residuals taken at large plants - correct answer -every 2 hours
Cl2 gas is extremely toxic and corrosive in what kind of atmosphere - correct answer -moist
Respiratory protection must be certified by what - correct answer -niosh national institute for
occupational safety health
WITH CORRECT ANSWERS 2025/2026
Delivered min. Working pressure - correct answer -35 psi
Rp backflow preventer will stop... - correct answer -back pressure and back siphon age
Gate valves have less... - correct answer -friction loss
Cavitation is caused by... - correct answer -excess pump speed
Hydrant flow - correct answer -(2.83)(d^2)(l)/(square root of h)=gpm
Min. Distribution pressure - correct answer -20 psi
Aquifer - correct answer -water bearing stratum of rock, sand, or gravel
Type of rupture or breakage that may occur when a pipe is unevenly supported along its length -
correct answer -beam breakage
Awwa's max distance between residential valves - correct answer -800 ft.
Min. Flushing velocity when unidirectional flushing method - correct answer -5 fps
Which type of level sensor requires an air supply - correct answer -bubbler tube
Mcl for chloride - correct answer -250 mg/l
,Two tier 1 violations - correct answer -acute risk to health
Purpose for metallic tracer tape - correct answer -locating protection of distribution pipe
Min. Backflow protection against a cross connection containing a contaminant that is dangerous
to health - correct answer -double check valve assembly
Reverse water flow caused by a vacuum is called... - correct answer -back siphon age
Min. Contact time when disinfecting water mains with the chlorine slug method - correct
answer -3 hours
Di pipe primarily used for river crossings and underwater intakes - correct answer -ball and
socket
A reduced pressure zone device consists of two spring loaded check valves with a... - correct
answer -pressure regulated relief located between them
A venturi meter has... - correct answer -two taps, the downstream tap is the high pressure tap
Anodes suspended in a tank are used to prevent... - correct answer -corrosion
Min height of well vent pipe - correct answer -36 inches
Test that determines if mains need cleaning or replacement - correct answer -fire flow test
,Water demand in a community is usually estimated on the basis of - correct answer -per capita
demand
Valves needed at pipe crosses - correct answer -three
Valves needed at pipe tees - correct answer -two
Min acceptable cl2 residual when using chloramines for disinfection - correct answer -.6 mg/l
Cl2 residual needed to disinfect well casings - correct answer -50 ml/l
Backflows are installed downstream from the what - correct answer -meter
Double check backflows offer what level of protection - correct answer -least
Rp backflows offer what level of protection - correct answer -medium
Rp backflows have what between two check valves - correct answer -relief valve
What offers the highest level of backflow protection - correct answer -air gap
Min and max distance backflows to be off ground - correct answer -12 min 30 inches max
What is a more powerful disinfectant than chloramines - correct answer -chlorine
What disinfectant is more persistent than chlorine - correct answer -chloramines
, Chloramines are more effective than chlorine against what - correct answer -biofilms
Main chlorination at 25-50 mg/l is held for how long - correct answer -24 hours
Min cl2 residual for main after 24 hour hold - correct answer -10 mg/l
Main slug method at 100 mg/l must be held for min of - correct answer -3 hours
Calcium hypochlorite can support a fire when stored close to what - correct answer -organics
If cl2 residual leaving plant falls below .20, how long do you have to correct the problem -
correct answer -4 hours, if corrected under 4 hours not a violation, but regulatory agency must
be notified
Convert f to c - correct answer -(f-32)/1.8
Convert c to f - correct answer -(c x 1.8) + 32
How many times a day are cl2 residuals taken at small plants - correct answer -3 times a day
How often are cl2 residuals taken at large plants - correct answer -every 2 hours
Cl2 gas is extremely toxic and corrosive in what kind of atmosphere - correct answer -moist
Respiratory protection must be certified by what - correct answer -niosh national institute for
occupational safety health
