D2 - WATER DISTRIBUTION OPERATOR EXAM (CALIFORNIA)
QUESTIONS WITH CORRECT ANSWERS 2025/2026
Three sources of supply - CORRECT ANSWER -Surface water treatment plants, Import/Purchased
water, and Wells.
Transmission Main - CORRECT ANSWER -A very large main designed to move water from one
part of the system to another.
Shut-Off Valve - CORRECT 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? - CORRECT ANSWER -Usually found connected to a
consumer's meter.
Why might a water company need to shut water off to a particular consumer? - CORRECT
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 - CORRECT ANSWER -Curb stop & Angle stop.
Meters - CORRECT ANSWER -Devices used to read consumer usage.
Where does a water company's property end - CORRECT ANSWER -At the consumer's meter.
Most common type of residential water meter and why? - CORRECT ANSWER -Positive
displacement meters, because they accurately measure all water that flows through them.
Three types of water systems - CORRECT ANSWER -Arterial loop, Grid, and Tree.
, Minimum acceptable PSI with a system - CORRECT ANSWER -20 PSI
Normal acceptable range of PSI within a system - CORRECT ANSWER -35 to 65 PSI
When must a pressure regulator be installed on a consumer's service line? - CORRECT ANSWER -
GREATER than 80 PSI.
What is the highest acceptable PSI within a system, before a pressure regulator needs to be
installed? - CORRECT ANSWER -80 PSI
Why are higher pressures generally not desired within a system? - CORRECT ANSWER -It can
damage plumbing fixtures.
Dynamic Pressure - CORRECT ANSWER -The pressure within a system when water is moving.
Six types of pipe found in a water distribution system - CORRECT ANSWER -Ductile Iron,
Concrete, Steel, Asbestos Cement, Plastic and Gray Cast Iron.
C-Value - CORRECT ANSWER -The measure of interior smoothness within a pipe.
What does a 140+ C-Value mean? - CORRECT ANSWER -Very smooth interior surface of a pipe
(Plastic, AC, Concrete)
What does a <100 C-Value mean? - CORRECT ANSWER -Very bad interior surface of a pipe
(Tuburculated old cast iron)
QUESTIONS WITH CORRECT ANSWERS 2025/2026
Three sources of supply - CORRECT ANSWER -Surface water treatment plants, Import/Purchased
water, and Wells.
Transmission Main - CORRECT ANSWER -A very large main designed to move water from one
part of the system to another.
Shut-Off Valve - CORRECT 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? - CORRECT ANSWER -Usually found connected to a
consumer's meter.
Why might a water company need to shut water off to a particular consumer? - CORRECT
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 - CORRECT ANSWER -Curb stop & Angle stop.
Meters - CORRECT ANSWER -Devices used to read consumer usage.
Where does a water company's property end - CORRECT ANSWER -At the consumer's meter.
Most common type of residential water meter and why? - CORRECT ANSWER -Positive
displacement meters, because they accurately measure all water that flows through them.
Three types of water systems - CORRECT ANSWER -Arterial loop, Grid, and Tree.
, Minimum acceptable PSI with a system - CORRECT ANSWER -20 PSI
Normal acceptable range of PSI within a system - CORRECT ANSWER -35 to 65 PSI
When must a pressure regulator be installed on a consumer's service line? - CORRECT ANSWER -
GREATER than 80 PSI.
What is the highest acceptable PSI within a system, before a pressure regulator needs to be
installed? - CORRECT ANSWER -80 PSI
Why are higher pressures generally not desired within a system? - CORRECT ANSWER -It can
damage plumbing fixtures.
Dynamic Pressure - CORRECT ANSWER -The pressure within a system when water is moving.
Six types of pipe found in a water distribution system - CORRECT ANSWER -Ductile Iron,
Concrete, Steel, Asbestos Cement, Plastic and Gray Cast Iron.
C-Value - CORRECT ANSWER -The measure of interior smoothness within a pipe.
What does a 140+ C-Value mean? - CORRECT ANSWER -Very smooth interior surface of a pipe
(Plastic, AC, Concrete)
What does a <100 C-Value mean? - CORRECT ANSWER -Very bad interior surface of a pipe
(Tuburculated old cast iron)
