ILLINOIS CLASS D WATER LICENSE EXAM 110
QUESTIONS & CORRECT ANSWERS LATEST
2026/2027
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
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
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
QUESTIONS & CORRECT ANSWERS LATEST
2026/2027
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
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
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
