Water Distribution Grade III Exam Questions and Answers
Who requires water operator certification in the United States? - -The EPA
-Which type of hydrant has no main valve but has a separate valve for each nozzle outlet? -
-Wet Barrel
-When is the best time to flush a distribution system? - -Late at night
-A broken water main can cause a loss of pressure in a distribution system. What kind of
problem can this create? - -Back siphonage
-If the water temperature increases, what affect does this have on chlorines ability to
disinfect water? - -It has no effect
-What is the cause of turbidity in water? - -Dissolved minerals
-It has been determined that a customers backflow device has failed, what steps should the
utility take? - -Notify customer to repair it immediately or service may be terminated
-What chemical method can a utility use to disinfect a water supply so it is safe to drink? -
-Sodium hypochlorite, calcium hypochlorite, ozone
-What is a sample called if an operator takes a sample in the distribution system to test for
chlorine or coliform? - -Grab sample
-What type of records should be kept daily in a water distribution system? - -Chlorine
residuals, flows, and time cards
-Which of the following provides a profile of hazardous substances or mixtures? - -MSDS
-Why should an operator use precautions when working with or around la hydro
pneumatic pressure tank? - -The high pressure in these tanks could injure the operator if
caution is not used
-What is in a surge tank that prevents water hammer? - -An air space
-If a monthly coliform sample was positive, what should the utility do first? - -Retest all
sites listed in the site sampling plan
-If a corrosion problem exists within a distribution system, what chemicals can be used to
correct this problem? - -Orthophosphates, caustic soda, lime & soda ash
-Elevated storage tanks are usually located in towns where the land is: - -Flat
, -Water storage tanks are designed to provide potable water during: - -Average and peak
demands, emergencies such as fires, normal activities
-A water storage tank is on a hill that is 115 ft in elevation above the first fire hydrant. The
storage tank measures 60 ft long, 50 ft wide and 40 ft tall. What is the pressure at the
hydrant if the tank is full? - -115ft elevation + 40ft tall tank = 155ft x .433 = 67psi
-An atmosphere is defined as oxygen deficient if it contains less than what percent oxygen
by volume? - -19.5
-A centrifugal pump should never be operated unless the impeller is submerged in water
or primed. What could cause a centrifugal pump to lose its prime? - -A malfunctioning foot
valve
-The primary drinking water standards apply to drinking water contaminants that may
have an adverse effect on - -Human Health
-When working inside a water storage tank, a person should always wear a safety harness
so that they may be rescued if they become injured or unconscious. How many people
should be standing by in case rescue is necessary? - -Two
-What a water storage tank is first brought on line it must be disinfected. It is generally
accepted that to disinfect a new storage tank, a chlorine solution of 200 mg/L should be
sprayed or brushed on all surface areas inside the tank and allowed to stand unused for at
least 30 minutes. Then what? - -Fill up tank, let it sit for 3-6 hours , test for coliform amd
take steps to put online if bacti is negative
-Where are DBP (disinfection byproducts) samples normally taken? - -In the distribution
system
-What type of water distribution system piping is least likely to corrode? - -Plastic
-Displacement water meters are smaller meters that are usually used for customer
services due to the fact they are designed for low flows. Name two types of displacement
meters. - -Nutating disc and piston meters
-What are some examples of velocity water meters? - -Insertion and electronic, venturi
and propeller, turbine
-A new customer wishes to connect to a utilities water system, but they have a large
swimming pool in their backyard. What type of backflow device should the utility require
this customer to install? - -Double check valve device
-When installing new water pipe, the pipe must have at least how many inches of cover? - -
30 inches
Who requires water operator certification in the United States? - -The EPA
-Which type of hydrant has no main valve but has a separate valve for each nozzle outlet? -
-Wet Barrel
-When is the best time to flush a distribution system? - -Late at night
-A broken water main can cause a loss of pressure in a distribution system. What kind of
problem can this create? - -Back siphonage
-If the water temperature increases, what affect does this have on chlorines ability to
disinfect water? - -It has no effect
-What is the cause of turbidity in water? - -Dissolved minerals
-It has been determined that a customers backflow device has failed, what steps should the
utility take? - -Notify customer to repair it immediately or service may be terminated
-What chemical method can a utility use to disinfect a water supply so it is safe to drink? -
-Sodium hypochlorite, calcium hypochlorite, ozone
-What is a sample called if an operator takes a sample in the distribution system to test for
chlorine or coliform? - -Grab sample
-What type of records should be kept daily in a water distribution system? - -Chlorine
residuals, flows, and time cards
-Which of the following provides a profile of hazardous substances or mixtures? - -MSDS
-Why should an operator use precautions when working with or around la hydro
pneumatic pressure tank? - -The high pressure in these tanks could injure the operator if
caution is not used
-What is in a surge tank that prevents water hammer? - -An air space
-If a monthly coliform sample was positive, what should the utility do first? - -Retest all
sites listed in the site sampling plan
-If a corrosion problem exists within a distribution system, what chemicals can be used to
correct this problem? - -Orthophosphates, caustic soda, lime & soda ash
-Elevated storage tanks are usually located in towns where the land is: - -Flat
, -Water storage tanks are designed to provide potable water during: - -Average and peak
demands, emergencies such as fires, normal activities
-A water storage tank is on a hill that is 115 ft in elevation above the first fire hydrant. The
storage tank measures 60 ft long, 50 ft wide and 40 ft tall. What is the pressure at the
hydrant if the tank is full? - -115ft elevation + 40ft tall tank = 155ft x .433 = 67psi
-An atmosphere is defined as oxygen deficient if it contains less than what percent oxygen
by volume? - -19.5
-A centrifugal pump should never be operated unless the impeller is submerged in water
or primed. What could cause a centrifugal pump to lose its prime? - -A malfunctioning foot
valve
-The primary drinking water standards apply to drinking water contaminants that may
have an adverse effect on - -Human Health
-When working inside a water storage tank, a person should always wear a safety harness
so that they may be rescued if they become injured or unconscious. How many people
should be standing by in case rescue is necessary? - -Two
-What a water storage tank is first brought on line it must be disinfected. It is generally
accepted that to disinfect a new storage tank, a chlorine solution of 200 mg/L should be
sprayed or brushed on all surface areas inside the tank and allowed to stand unused for at
least 30 minutes. Then what? - -Fill up tank, let it sit for 3-6 hours , test for coliform amd
take steps to put online if bacti is negative
-Where are DBP (disinfection byproducts) samples normally taken? - -In the distribution
system
-What type of water distribution system piping is least likely to corrode? - -Plastic
-Displacement water meters are smaller meters that are usually used for customer
services due to the fact they are designed for low flows. Name two types of displacement
meters. - -Nutating disc and piston meters
-What are some examples of velocity water meters? - -Insertion and electronic, venturi
and propeller, turbine
-A new customer wishes to connect to a utilities water system, but they have a large
swimming pool in their backyard. What type of backflow device should the utility require
this customer to install? - -Double check valve device
-When installing new water pipe, the pipe must have at least how many inches of cover? - -
30 inches
