1
Water Distribution Questions with Answers
(100% Correct Answers)
delivered min. working pressure— Answer: 35 PSI
RP backflow preventer will stop...— Answer: back pressure and back siphon
age
gate valves have less...— Answer: friction loss
cavitation is caused by...— Answer: excess pump speed
hydrant flow— Answer: (2.83)(D^2)(l)/(square root of H)=GPM
min. distribution pressure— Answer: 20 PSI
aquifer— 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— Answer: beam breakage
AWWA's max distance between residential valves— Answer: 800 ft.
min. flushing velocity when unidirectional flushing method— Answer: 5 FPS
which type of level sensor requires an air supply— Answer: bubbler tube
MCL for chloride— Answer: 250 mg/L
two tier 1 violations— Answer: acute risk to health
purpose for metallic tracer tape— Answer: locating protection of distribution
pipe
min. backflow protection against a cross connection containing a contaminant
that is dangerous to health— Answer: double check valve assembly
reverse water flow caused by a vacuum is called...— Answer: back siphon age
,2
min. contact time when disinfecting water mains with the chlorine slug
method— Answer: 3 hours
DI pipe primarily used for river crossings and underwater intakes— Answer:
ball and socket
a reduced pressure zone device consists of two spring loaded check valves with
a...— Answer: pressure regulated relief located between them
a venturi meter has...— Answer: two taps, the downstream tap is the high
pressure tap
anodes suspended in a tank are used to prevent...— Answer: corrosion
min height of well vent pipe— Answer: 36 inches
test that determines if mains need cleaning or replacement— Answer: fire flow
test
water demand in a community is usually estimated on the basis of— Answer:
per capita demand
valves needed at pipe crosses— Answer: three
valves needed at pipe tees— Answer: two
min acceptable CL2 residual when using chloramines for disinfection—
Answer: .6 mg/L
CL2 residual needed to disinfect well casings— Answer: 50 ml/L
backflows are installed downstream from the what— Answer: meter
double check backflows offer what level of protection— Answer: least
RP backflows offer what level of protection— Answer: medium
RP backflows have what between two check valves— Answer: relief valve
,3
what offers the highest level of backflow protection— Answer: air gap
min and max distance backflows to be off ground— Answer: 12 min 30 inches
max
what is a more powerful disinfectant than chloramines— Answer: chlorine
what disinfectant is more persistent than chlorine— Answer: chloramines
chloramines are more effective than chlorine against what— Answer: biofilms
main chlorination at 25-50 mg/L is held for how long— Answer: 24 hours
min CL2 residual for main after 24 hour hold— Answer: 10 mg/L
main slug method at 100 mg/l must be held for min of— Answer: 3 hours
calcium hypochlorite can support a fire when stored close to what— Answer:
organics
if CL2 residual leaving plant falls below .20, how long do you have to correct
the problem— Answer: 4 hours, if corrected under 4 hours not a violation, but
regulatory agency must be notified
convert F to C— Answer: (F-32)/1.8
convert C to F— Answer: (C x 1.8) + 32
how many times a day are CL2 residuals taken at small plants— Answer: 3
times a day
how often are CL2 residuals taken at large plants— Answer: every 2 hours
CL2 gas is extremely toxic and corrosive in what kind of atmosphere—
Answer: moist
respiratory protection must be certified by what— Answer: niosh national
institute for occupational safety health
, 4
when CL2 gas exceeds what level a full face respirator is needed— Answer: .5
ppm
respiratory protection needed during an uncontrolled release— Answer: SCBA
how often should reservoirs be inspected— Answer: weekly
how often should valves be inspected— Answer: annually
how often should valve boxes be inspected— Answer: annually
Why should ARV's be inspected after heavy rains or floods— Answer:
submersion danger
what should you do if you suspect reservoir vandalism— Answer: shut it down
national secondary drinking water regulations apply to contaminants that effect
what— Answer: aesthetic quality of drinking water
lead and copper samples are taken from first draw, cold, kitchen or bath at
what min and max times— Answer: min 6 hours, max 12 hours
What survey collects the following, location, date, name, building rep, water
source, piping system, points of interconnection, special equipment, remarks,
recommendations— Answer: cross connection survey
what 2 types of backflows are used at dangerous applications with health
hazard potential— Answer: air gap or RP
Two places pipe leaks typically originate from— Answer: weakened joint or
fitting, damaged or corroded portion of the pipe
what is done when no specific reason is found for significant water loss—
Answer: water control study
pressure surveys are conducted to indicate what— Answer: hydraulic efficiency
Water Distribution Questions with Answers
(100% Correct Answers)
delivered min. working pressure— Answer: 35 PSI
RP backflow preventer will stop...— Answer: back pressure and back siphon
age
gate valves have less...— Answer: friction loss
cavitation is caused by...— Answer: excess pump speed
hydrant flow— Answer: (2.83)(D^2)(l)/(square root of H)=GPM
min. distribution pressure— Answer: 20 PSI
aquifer— 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— Answer: beam breakage
AWWA's max distance between residential valves— Answer: 800 ft.
min. flushing velocity when unidirectional flushing method— Answer: 5 FPS
which type of level sensor requires an air supply— Answer: bubbler tube
MCL for chloride— Answer: 250 mg/L
two tier 1 violations— Answer: acute risk to health
purpose for metallic tracer tape— Answer: locating protection of distribution
pipe
min. backflow protection against a cross connection containing a contaminant
that is dangerous to health— Answer: double check valve assembly
reverse water flow caused by a vacuum is called...— Answer: back siphon age
,2
min. contact time when disinfecting water mains with the chlorine slug
method— Answer: 3 hours
DI pipe primarily used for river crossings and underwater intakes— Answer:
ball and socket
a reduced pressure zone device consists of two spring loaded check valves with
a...— Answer: pressure regulated relief located between them
a venturi meter has...— Answer: two taps, the downstream tap is the high
pressure tap
anodes suspended in a tank are used to prevent...— Answer: corrosion
min height of well vent pipe— Answer: 36 inches
test that determines if mains need cleaning or replacement— Answer: fire flow
test
water demand in a community is usually estimated on the basis of— Answer:
per capita demand
valves needed at pipe crosses— Answer: three
valves needed at pipe tees— Answer: two
min acceptable CL2 residual when using chloramines for disinfection—
Answer: .6 mg/L
CL2 residual needed to disinfect well casings— Answer: 50 ml/L
backflows are installed downstream from the what— Answer: meter
double check backflows offer what level of protection— Answer: least
RP backflows offer what level of protection— Answer: medium
RP backflows have what between two check valves— Answer: relief valve
,3
what offers the highest level of backflow protection— Answer: air gap
min and max distance backflows to be off ground— Answer: 12 min 30 inches
max
what is a more powerful disinfectant than chloramines— Answer: chlorine
what disinfectant is more persistent than chlorine— Answer: chloramines
chloramines are more effective than chlorine against what— Answer: biofilms
main chlorination at 25-50 mg/L is held for how long— Answer: 24 hours
min CL2 residual for main after 24 hour hold— Answer: 10 mg/L
main slug method at 100 mg/l must be held for min of— Answer: 3 hours
calcium hypochlorite can support a fire when stored close to what— Answer:
organics
if CL2 residual leaving plant falls below .20, how long do you have to correct
the problem— Answer: 4 hours, if corrected under 4 hours not a violation, but
regulatory agency must be notified
convert F to C— Answer: (F-32)/1.8
convert C to F— Answer: (C x 1.8) + 32
how many times a day are CL2 residuals taken at small plants— Answer: 3
times a day
how often are CL2 residuals taken at large plants— Answer: every 2 hours
CL2 gas is extremely toxic and corrosive in what kind of atmosphere—
Answer: moist
respiratory protection must be certified by what— Answer: niosh national
institute for occupational safety health
, 4
when CL2 gas exceeds what level a full face respirator is needed— Answer: .5
ppm
respiratory protection needed during an uncontrolled release— Answer: SCBA
how often should reservoirs be inspected— Answer: weekly
how often should valves be inspected— Answer: annually
how often should valve boxes be inspected— Answer: annually
Why should ARV's be inspected after heavy rains or floods— Answer:
submersion danger
what should you do if you suspect reservoir vandalism— Answer: shut it down
national secondary drinking water regulations apply to contaminants that effect
what— Answer: aesthetic quality of drinking water
lead and copper samples are taken from first draw, cold, kitchen or bath at
what min and max times— Answer: min 6 hours, max 12 hours
What survey collects the following, location, date, name, building rep, water
source, piping system, points of interconnection, special equipment, remarks,
recommendations— Answer: cross connection survey
what 2 types of backflows are used at dangerous applications with health
hazard potential— Answer: air gap or RP
Two places pipe leaks typically originate from— Answer: weakened joint or
fitting, damaged or corroded portion of the pipe
what is done when no specific reason is found for significant water loss—
Answer: water control study
pressure surveys are conducted to indicate what— Answer: hydraulic efficiency
