1|Page
Class D Water Operator 2025 Latest Ultimate Exam Prep
Test Bank with 900 Questions and Answers with
Definition of Terms/ Water Operator Class D License
Exam Latest (Most Recent Qs)
Two Towers are both 125 feet high, when full, contain 122
feet of water. Tower 1 holds 150,000 gallons. Tower 2
holds 500,000 gallons. Each has a pressure gauge at the
base. Which will register the most pressure in psi? -
...ANSWER...✓✓ Both will be equal
If the water level in tower 1 is 118 feet what will the
pressure reading be at the base - ...ANSWER...✓✓ 51.1 psi
What is the definition of potable water - ...ANSWER...✓✓
Water that does not contain objectable pollution,
contamination, or infective agents and is considered safe
for drinking
What is the first item used when installing a service line
to a customer? - ...ANSWER...✓✓ Corporation stop
,2|Page
If a meter to a residence is located in the basement what
should be located between the water main and the house
- ...ANSWER...✓✓ curb stop
A 5/8" x 3/4" water meter serves a residence. Over a
period of years the meter __________ in recording actual
water used - ...ANSWER...✓✓ Decreases
To isolate part of a distribution system what type of valve
is commonly used? - ...ANSWER...✓✓ Gate valve
Trihalomethanes (THMs) are caused by? - ...ANSWER...✓✓
Reaction of chlorinated water with numeric materials
found in surface water sources
The longer the contact time water and chlorine residuals
enjoy the ________ the THM level will probably be -
...ANSWER...✓✓ Higher
THM's should be eliminated from finished water because
they cause ? - ...ANSWER...✓✓ Cancer
, 3|Page
The maximum contaminant level for THM's is? -
...ANSWER...✓✓ .080 mg/l
When collecting THM samples one sample must be taken
at a site where the water has been in the distribution
system the longest time - ...ANSWER...✓✓ True
An applicant for a class d test who has graduated high
school but has no approved training credits must have
____________ "hands on" experience - ...ANSWER...✓✓ 6
months
What type of water main is most likely to become
contaminated from gasoline saturated soil -
...ANSWER...✓✓ PVC
What type of materials must not be used as backfill for
water mains? - ...ANSWER...✓✓ Cinders
Nitrate in levels above _________ mg/L can cause "blue
baby" disease - ...ANSWER...✓✓ 10
Class D Water Operator 2025 Latest Ultimate Exam Prep
Test Bank with 900 Questions and Answers with
Definition of Terms/ Water Operator Class D License
Exam Latest (Most Recent Qs)
Two Towers are both 125 feet high, when full, contain 122
feet of water. Tower 1 holds 150,000 gallons. Tower 2
holds 500,000 gallons. Each has a pressure gauge at the
base. Which will register the most pressure in psi? -
...ANSWER...✓✓ Both will be equal
If the water level in tower 1 is 118 feet what will the
pressure reading be at the base - ...ANSWER...✓✓ 51.1 psi
What is the definition of potable water - ...ANSWER...✓✓
Water that does not contain objectable pollution,
contamination, or infective agents and is considered safe
for drinking
What is the first item used when installing a service line
to a customer? - ...ANSWER...✓✓ Corporation stop
,2|Page
If a meter to a residence is located in the basement what
should be located between the water main and the house
- ...ANSWER...✓✓ curb stop
A 5/8" x 3/4" water meter serves a residence. Over a
period of years the meter __________ in recording actual
water used - ...ANSWER...✓✓ Decreases
To isolate part of a distribution system what type of valve
is commonly used? - ...ANSWER...✓✓ Gate valve
Trihalomethanes (THMs) are caused by? - ...ANSWER...✓✓
Reaction of chlorinated water with numeric materials
found in surface water sources
The longer the contact time water and chlorine residuals
enjoy the ________ the THM level will probably be -
...ANSWER...✓✓ Higher
THM's should be eliminated from finished water because
they cause ? - ...ANSWER...✓✓ Cancer
, 3|Page
The maximum contaminant level for THM's is? -
...ANSWER...✓✓ .080 mg/l
When collecting THM samples one sample must be taken
at a site where the water has been in the distribution
system the longest time - ...ANSWER...✓✓ True
An applicant for a class d test who has graduated high
school but has no approved training credits must have
____________ "hands on" experience - ...ANSWER...✓✓ 6
months
What type of water main is most likely to become
contaminated from gasoline saturated soil -
...ANSWER...✓✓ PVC
What type of materials must not be used as backfill for
water mains? - ...ANSWER...✓✓ Cinders
Nitrate in levels above _________ mg/L can cause "blue
baby" disease - ...ANSWER...✓✓ 10
