Water Distribution | Questions with 100% Verified Answers | Latest Update 2026/2027

Water Distribution | Questions with 100% Verified Answers |
Latest Update 2026/2027
Question: delivered min. working pressure
Answer: 35 PSI

Question: RP backflow preventer will stop...
Answer: back pressure and back siphon age

Question: gate valves have less...
Answer: friction loss

Question: cavitation is caused by...
Answer: excess pump speed

Question: hydrant flow
Answer: (2.83)(D^2)(l)/(square root of H)=GPM

Question: min. distribution pressure
Answer: 20 PSI

Question: aquifer
Answer: water bearing stratum of rock, sand, or gravel

Question: type of rupture or breakage that may occur when a pipe is unevenly supported along its length
Answer: beam breakage

Question: AWWA's max distance between residential valves
Answer: 800 ft.

Question: min. flushing velocity when unidirectional flushing method
Answer: 5 FPS

Question: which type of level sensor requires an air supply
Answer: bubbler tube

Question: MCL for chloride
Answer: 250 mg/L

Question: two tier 1 violations
Answer: acute risk to health

Question: purpose for metallic tracer tape
Answer: locating protection of distribution pipe

,Question: min. backflow protection against a cross connection containing a contaminant that is dangerous to
health
Answer: double check valve assembly

Question: reverse water flow caused by a vacuum is called...
Answer: back siphon age

Question: min. contact time when disinfecting water mains with the chlorine slug method
Answer: 3 hours

Question: DI pipe primarily used for river crossings and underwater intakes
Answer: ball and socket

Question: a reduced pressure zone device consists of two spring loaded check valves with a...
Answer: pressure regulated relief located between them

Question: a venturi meter has...
Answer: two taps, the downstream tap is the high pressure tap

Question: anodes suspended in a tank are used to prevent...
Answer: corrosion

Question: min height of well vent pipe
Answer: 36 inches

Question: test that determines if mains need cleaning or replacement
Answer: fire flow test

Question: water demand in a community is usually estimated on the basis of
Answer: per capita demand

Question: valves needed at pipe crosses
Answer: three

Question: valves needed at pipe tees
Answer: two

Question: min acceptable CL2 residual when using chloramines for disinfection
Answer: .6 mg/L

Question: CL2 residual needed to disinfect well casings
Answer: 50 ml/L

Question: backflows are installed downstream from the what
Answer: meter

,Question: double check backflows offer what level of protection
Answer: least

Question: RP backflows offer what level of protection
Answer: medium

Question: RP backflows have what between two check valves
Answer: relief valve

Question: what offers the highest level of backflow protection
Answer: air gap

Question: min and max distance backflows to be off ground
Answer: 12 min 30 inches max

Question: what is a more powerful disinfectant than chloramines
Answer: chlorine

Question: what disinfectant is more persistent than chlorine
Answer: chloramines

Question: chloramines are more effective than chlorine against what
Answer: biofilms

Question: main chlorination at 25-50 mg/L is held for how long
Answer: 24 hours

Question: min CL2 residual for main after 24 hour hold
Answer: 10 mg/L

Question: main slug method at 100 mg/l must be held for min of
Answer: 3 hours

Question: calcium hypochlorite can support a fire when stored close to what
Answer: organics

Question: 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

Question: convert F to C
Answer: (F-32)/1.8

Question: convert C to F
Answer: (C x 1.8) + 32

, Question: how many times a day are CL2 residuals taken at small plants
Answer: 3 times a day

Question: how often are CL2 residuals taken at large plants
Answer: every 2 hours

Question: CL2 gas is extremely toxic and corrosive in what kind of atmosphere
Answer: moist

Question: respiratory protection must be certified by what
Answer: niosh national institute for occupational safety health

Question: when CL2 gas exceeds what level a full face respirator is needed
Answer: .5 ppm

Question: respiratory protection needed during an uncontrolled release
Answer: SCBA

Question: how often should reservoirs be inspected
Answer: weekly

Question: how often should valves be inspected
Answer: annually

Question: how often should valve boxes be inspected
Answer: annually

Question: Why should ARV's be inspected after heavy rains or floods
Answer: submersion danger

Question: what should you do if you suspect reservoir vandalism
Answer: shut it down

Question: national secondary drinking water regulations apply to contaminants that effect what
Answer: aesthetic quality of drinking water

Question: 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

Question: 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

Question: what 2 types of backflows are used at dangerous applications with health hazard potential
Answer: air gap or RP