ILLINOIS CLASS D WATER LICENSE EXAM (ACTUAL EXAM 2025) | ALL QUESTIONS AND
CORRECT ANSWERS | VERIFIED ANSWERS | ALREADY GRADED A+ | LATEST EXAM
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
, ILLINOIS CLASS D WATER LICENSE EXAM (ACTUAL EXAM 2025) | ALL QUESTIONS AND
CORRECT ANSWERS | VERIFIED ANSWERS | ALREADY GRADED A+ | LATEST EXAM
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
The higher the "C" factor of a pipe the _____________ the pipe and the greater the carrying capacity of
the pipe - (ANSWER)Smoother
A distribution system that is "looped" instead of having dead ends will help prevent - (ANSWER)Tastes
and odors, "dirty" water, and chlorine depletion
CORRECT ANSWERS | VERIFIED ANSWERS | ALREADY GRADED A+ | LATEST EXAM
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
, ILLINOIS CLASS D WATER LICENSE EXAM (ACTUAL EXAM 2025) | ALL QUESTIONS AND
CORRECT ANSWERS | VERIFIED ANSWERS | ALREADY GRADED A+ | LATEST EXAM
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
The higher the "C" factor of a pipe the _____________ the pipe and the greater the carrying capacity of
the pipe - (ANSWER)Smoother
A distribution system that is "looped" instead of having dead ends will help prevent - (ANSWER)Tastes
and odors, "dirty" water, and chlorine depletion
