ILLINOIS CLASS D WATER LICENSE TEST 2025 NEWEST
ACTUAL EXAM QUESTIONS AND CORRECT ACCURATE
ANSWERS
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
A boil order must be issued if systems pressure drops below 20 psi or if contaminated of any part
of the system is suspected. Why? -ANSWER: It is a regulation of the IEPA, and to protect the
health of water consumers
A boil order should be issued for? -ANSWER: Until further notice
Upon the issuance of a boil order the IEPA regional office should be notified of the order
because ________________? -ANSWER: It's a state regulation
The "C" factor of a pipe is _______________? -ANSWER: The smoothness of the interior of a
pipe
ACTUAL EXAM QUESTIONS AND CORRECT ACCURATE
ANSWERS
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
A boil order must be issued if systems pressure drops below 20 psi or if contaminated of any part
of the system is suspected. Why? -ANSWER: It is a regulation of the IEPA, and to protect the
health of water consumers
A boil order should be issued for? -ANSWER: Until further notice
Upon the issuance of a boil order the IEPA regional office should be notified of the order
because ________________? -ANSWER: It's a state regulation
The "C" factor of a pipe is _______________? -ANSWER: The smoothness of the interior of a
pipe
