1|Page
D2 - Water Distribution Operator Exam (California)
LATEST QUESTIONS AND CORRECT DETAILED
SOLUTIONS ALL WITH DETAILED
three sources of supply ......ANSWER......Surface water treatment plants,
Import/Purchased water, and Wells.
Transmission Main ......ANSWER......A very large main designed to move
water from one part of the system to another.
Shut-Off Valve ......ANSWER......A type of valve the water company uses
when they need to turn water off to a particular consumer.
Where is a Shut-Off Valve typically located? ......ANSWER......Usually
found connected to a consumer's meter.
Why might a water company need to shut water off to a particular
consumer? ......ANSWER......Because of a request to connect or
disconnect, for repairs, or as a result of non payment.
two most common types of Shut-Off Valves ......ANSWER......Curb stop &
Angle stop.
pg. 1
,2|Page
Meters ......ANSWER......Devices used to read consumer usage.
where does a water company's property end ......ANSWER......At the
consumer's meter.
most common type of residential water meter and why?
......ANSWER......Positive displacement meters, because they accurately
measure all water that flows through them.
three types of water systems ......ANSWER......Arterial loop, Grid, and
Tree.
minimum acceptable PSI with a system ......ANSWER......20 PSI
normal acceptable range of PSI within a system ......ANSWER......35 to
65 PSI
When must a pressure regulator be installed on a consumer's service
line? ......ANSWER......GREATER than 80 PSI.
What is the highest acceptable PSI within a system, before a pressure
regulator needs to be installed? ......ANSWER......80 PSI
pg. 2
, 3|Page
Why are higher pressures generally not desired within a system?
......ANSWER......It can damage plumbing fixtures.
Dynamic Pressure ......ANSWER......The pressure within a system when
water is moving.
six types of pipe found in a water distribution system
......ANSWER......Ductile Iron, Concrete, Steel, Asbestos Cement, Plastic
and Gray Cast Iron.
C-Value ......ANSWER......The measure of interior smoothness within a
pipe.
What does a 140+ C-Value mean? ......ANSWER......Very smooth interior
surface of a pipe (Plastic, AC, Concrete)
What does a <100 C-Value mean? ......ANSWER......Very bad interior
surface of a pipe (Tuburculated old cast iron)
What is a Pnetrometer? ......ANSWER......A tool for measuring the
compressive strength of soil.
What is a Competent Person? ......ANSWER......An individual with
excavation knowledge and training who is in charge of an excavation
job, and who has the power to start work in the event of a hazard
pg. 3
D2 - Water Distribution Operator Exam (California)
LATEST QUESTIONS AND CORRECT DETAILED
SOLUTIONS ALL WITH DETAILED
three sources of supply ......ANSWER......Surface water treatment plants,
Import/Purchased water, and Wells.
Transmission Main ......ANSWER......A very large main designed to move
water from one part of the system to another.
Shut-Off Valve ......ANSWER......A type of valve the water company uses
when they need to turn water off to a particular consumer.
Where is a Shut-Off Valve typically located? ......ANSWER......Usually
found connected to a consumer's meter.
Why might a water company need to shut water off to a particular
consumer? ......ANSWER......Because of a request to connect or
disconnect, for repairs, or as a result of non payment.
two most common types of Shut-Off Valves ......ANSWER......Curb stop &
Angle stop.
pg. 1
,2|Page
Meters ......ANSWER......Devices used to read consumer usage.
where does a water company's property end ......ANSWER......At the
consumer's meter.
most common type of residential water meter and why?
......ANSWER......Positive displacement meters, because they accurately
measure all water that flows through them.
three types of water systems ......ANSWER......Arterial loop, Grid, and
Tree.
minimum acceptable PSI with a system ......ANSWER......20 PSI
normal acceptable range of PSI within a system ......ANSWER......35 to
65 PSI
When must a pressure regulator be installed on a consumer's service
line? ......ANSWER......GREATER than 80 PSI.
What is the highest acceptable PSI within a system, before a pressure
regulator needs to be installed? ......ANSWER......80 PSI
pg. 2
, 3|Page
Why are higher pressures generally not desired within a system?
......ANSWER......It can damage plumbing fixtures.
Dynamic Pressure ......ANSWER......The pressure within a system when
water is moving.
six types of pipe found in a water distribution system
......ANSWER......Ductile Iron, Concrete, Steel, Asbestos Cement, Plastic
and Gray Cast Iron.
C-Value ......ANSWER......The measure of interior smoothness within a
pipe.
What does a 140+ C-Value mean? ......ANSWER......Very smooth interior
surface of a pipe (Plastic, AC, Concrete)
What does a <100 C-Value mean? ......ANSWER......Very bad interior
surface of a pipe (Tuburculated old cast iron)
What is a Pnetrometer? ......ANSWER......A tool for measuring the
compressive strength of soil.
What is a Competent Person? ......ANSWER......An individual with
excavation knowledge and training who is in charge of an excavation
job, and who has the power to start work in the event of a hazard
pg. 3
