Massachusetts Water Distribution Grade
1 Exam
The Safe Drinking Water Act is primarily enforced at the federal level by the Correct
answer: Environmental Protection Agency (EPA). The EPA sets national standards for
drinking water quality under the SDWA.
Water mains should generally be laid with at least ___ feet of cover to prevent
freezing. Correct answer: 4.5. This depth provides protection from frost penetration in
most Massachusetts climates.
The cross-connection control program is primarily intended to prevent Correct answer:
Backflow. Backflow is the reverse flow of water, potentially contaminating the potable
system.
The type of valve best suited for regulating flow is a Correct answer: Butterfly valve.
While not ideal for throttling long-term, butterfly valves are commonly used for flow
regulation in water distribution.
The disinfection residual in the distribution system should be measurable at Correct
answer: The farthest point in the system. This ensures disinfectant protection
throughout the entire network.
A "blow-off" valve is typically used to Correct answer: Scour or flush a main. It is
installed at low points to remove sediment.
The most common cause of pipe joint failure is Correct answer: Improper bedding.
Adequate bedding and support are critical for pipe integrity.
Before entering a confined space, the atmosphere must be tested for Correct answer:
Oxygen content, flammable gases, and toxic vapors. All three are essential safety
checks.
,The minimum pressure in a distribution system under normal conditions should
be Correct answer: 20 psi. This prevents contaminants from being drawn into the
system.
The primary purpose of a check valve is to Correct answer: Allow flow in one
direction only. It prevents backflow.
Unaccounted-for water includes water that is Correct answer: Lost through leaks,
used for flushing, and unauthorized consumption. All are components of
unaccounted-for water.
The C-factor is a measure of Correct answer: The roughness of a pipe's interior. A
higher C-factor indicates a smoother pipe.
A pressure gauge reading that is consistently low could indicate Correct answer: A
major leak on the system. It signifies a loss of system pressure.
The best time to perform a leak detection survey is Correct answer: During early
morning hours. When water usage is low, leak sounds are more detectable.
Chlorine is added to water primarily to Correct answer: Disinfect and kill pathogens.
This is its primary public health function.
The maximum contaminant level (MCL) for a substance is Correct answer: The highest
allowable concentration in drinking water. It is a legally enforceable standard.
A fire hydrant with a blue bonnet typically indicates Correct answer: A flow capacity of
1500 GPM or greater. Color coding indicates flow capacity.
Before cutting into a main for a repair, you must Correct answer: Isolate the section
and disinfect all tools. This ensures safety and water quality.
The most likely result of excessive pumping from a well is Correct answer: A
drawdown of the water table. Over-pumping lowers the groundwater level.
,Water hammer is caused by Correct answer: A sudden change in water velocity. This
creates destructive pressure surges.
The primary purpose of thrust blocks is to Correct answer: Absorb axial thrust forces
at fittings. They prevent joints from separating.
A corporation stop is installed Correct answer: At the main, connecting the service
line. It is the utility's shut-off for a service connection.
The minimum separation between a water main and a sewer line is Correct answer: 10
feet horizontally. If crossing, the water main should be at least 18 inches above the
sewer.
Coliform bacteria in a distribution sample indicate Correct answer: Possible
contamination and potential presence of pathogens. They are indicator organisms.
The best method for locating a suspected service leak is Correct answer: Using a
ground microphone or acoustic leak detector. These tools amplify the sound of
leaking water.
A "shutdown" refers to Correct answer: Isolating a section of the main for repair. It is
a planned de-pressurization of a line.
The primary health concern with lead in drinking water is Correct answer: Impaired
cognitive development in children. It is a potent neurotoxin.
To safely add chlorine gas to water, you must use Correct answer: An ejector to create
a vacuum. This pulls the gas into the water stream safely.
The Standard Fire Hydrant outlet size is Correct answer: 2.5 inches. This is the standard
hose connection size.
The proper tool for cutting a large-diameter cast-iron pipe is a Correct answer:
Pneumatic cut-off saw. It provides the power needed for such dense material.
, A "strainer" is used on a suction pipe to Correct answer: Prevent debris from entering
the pump. It protects the pump internals.
The type of pump most commonly used for boosting pressure in a distribution system is
a Correct answer: Centrifugal pump. It is well-suited for this application.
When disinfecting a new water main, the chlorine concentration must be at
least Correct answer: 50 mg/L. This is a typical required strength for new main
disinfection.
The minimum acceptable chlorine residual at the farthest point in the system is Correct
answer: 0.2 mg/L. This ensures ongoing disinfection.
The primary purpose of a storage tank is to Correct answer: Meet peak demand and
maintain system pressure. It provides capacity and hydraulic stability.
A sample collected for bacteriological analysis should be Correct answer: Collected in
a sterile bottle with sodium thiosulfate. The thiosulfate neutralizes any chlorine
residual.
A positive displacement pump Correct answer: Delivers a constant volume
regardless of pressure. Its output is relatively constant.
The process of removing air from a pump casing is called Correct answer: Priming. A
centrifugal pump must be primed to operate.
The appropriate backfill material for a pipe trench is Correct answer: Select, clean,
granular material. It provides proper support and drainage.
The most common type of joint for PVC pressure pipe is a Correct answer: Gasketed
bell-and-spigot joint. It provides a push-on, watertight seal.
The term "MGD" stands for Correct answer: Million Gallons per Day. It is a unit of
flow.
1 Exam
The Safe Drinking Water Act is primarily enforced at the federal level by the Correct
answer: Environmental Protection Agency (EPA). The EPA sets national standards for
drinking water quality under the SDWA.
Water mains should generally be laid with at least ___ feet of cover to prevent
freezing. Correct answer: 4.5. This depth provides protection from frost penetration in
most Massachusetts climates.
The cross-connection control program is primarily intended to prevent Correct answer:
Backflow. Backflow is the reverse flow of water, potentially contaminating the potable
system.
The type of valve best suited for regulating flow is a Correct answer: Butterfly valve.
While not ideal for throttling long-term, butterfly valves are commonly used for flow
regulation in water distribution.
The disinfection residual in the distribution system should be measurable at Correct
answer: The farthest point in the system. This ensures disinfectant protection
throughout the entire network.
A "blow-off" valve is typically used to Correct answer: Scour or flush a main. It is
installed at low points to remove sediment.
The most common cause of pipe joint failure is Correct answer: Improper bedding.
Adequate bedding and support are critical for pipe integrity.
Before entering a confined space, the atmosphere must be tested for Correct answer:
Oxygen content, flammable gases, and toxic vapors. All three are essential safety
checks.
,The minimum pressure in a distribution system under normal conditions should
be Correct answer: 20 psi. This prevents contaminants from being drawn into the
system.
The primary purpose of a check valve is to Correct answer: Allow flow in one
direction only. It prevents backflow.
Unaccounted-for water includes water that is Correct answer: Lost through leaks,
used for flushing, and unauthorized consumption. All are components of
unaccounted-for water.
The C-factor is a measure of Correct answer: The roughness of a pipe's interior. A
higher C-factor indicates a smoother pipe.
A pressure gauge reading that is consistently low could indicate Correct answer: A
major leak on the system. It signifies a loss of system pressure.
The best time to perform a leak detection survey is Correct answer: During early
morning hours. When water usage is low, leak sounds are more detectable.
Chlorine is added to water primarily to Correct answer: Disinfect and kill pathogens.
This is its primary public health function.
The maximum contaminant level (MCL) for a substance is Correct answer: The highest
allowable concentration in drinking water. It is a legally enforceable standard.
A fire hydrant with a blue bonnet typically indicates Correct answer: A flow capacity of
1500 GPM or greater. Color coding indicates flow capacity.
Before cutting into a main for a repair, you must Correct answer: Isolate the section
and disinfect all tools. This ensures safety and water quality.
The most likely result of excessive pumping from a well is Correct answer: A
drawdown of the water table. Over-pumping lowers the groundwater level.
,Water hammer is caused by Correct answer: A sudden change in water velocity. This
creates destructive pressure surges.
The primary purpose of thrust blocks is to Correct answer: Absorb axial thrust forces
at fittings. They prevent joints from separating.
A corporation stop is installed Correct answer: At the main, connecting the service
line. It is the utility's shut-off for a service connection.
The minimum separation between a water main and a sewer line is Correct answer: 10
feet horizontally. If crossing, the water main should be at least 18 inches above the
sewer.
Coliform bacteria in a distribution sample indicate Correct answer: Possible
contamination and potential presence of pathogens. They are indicator organisms.
The best method for locating a suspected service leak is Correct answer: Using a
ground microphone or acoustic leak detector. These tools amplify the sound of
leaking water.
A "shutdown" refers to Correct answer: Isolating a section of the main for repair. It is
a planned de-pressurization of a line.
The primary health concern with lead in drinking water is Correct answer: Impaired
cognitive development in children. It is a potent neurotoxin.
To safely add chlorine gas to water, you must use Correct answer: An ejector to create
a vacuum. This pulls the gas into the water stream safely.
The Standard Fire Hydrant outlet size is Correct answer: 2.5 inches. This is the standard
hose connection size.
The proper tool for cutting a large-diameter cast-iron pipe is a Correct answer:
Pneumatic cut-off saw. It provides the power needed for such dense material.
, A "strainer" is used on a suction pipe to Correct answer: Prevent debris from entering
the pump. It protects the pump internals.
The type of pump most commonly used for boosting pressure in a distribution system is
a Correct answer: Centrifugal pump. It is well-suited for this application.
When disinfecting a new water main, the chlorine concentration must be at
least Correct answer: 50 mg/L. This is a typical required strength for new main
disinfection.
The minimum acceptable chlorine residual at the farthest point in the system is Correct
answer: 0.2 mg/L. This ensures ongoing disinfection.
The primary purpose of a storage tank is to Correct answer: Meet peak demand and
maintain system pressure. It provides capacity and hydraulic stability.
A sample collected for bacteriological analysis should be Correct answer: Collected in
a sterile bottle with sodium thiosulfate. The thiosulfate neutralizes any chlorine
residual.
A positive displacement pump Correct answer: Delivers a constant volume
regardless of pressure. Its output is relatively constant.
The process of removing air from a pump casing is called Correct answer: Priming. A
centrifugal pump must be primed to operate.
The appropriate backfill material for a pipe trench is Correct answer: Select, clean,
granular material. It provides proper support and drainage.
The most common type of joint for PVC pressure pipe is a Correct answer: Gasketed
bell-and-spigot joint. It provides a push-on, watertight seal.
The term "MGD" stands for Correct answer: Million Gallons per Day. It is a unit of
flow.
