Illinois Class D Water License Questions with Detailed Verified Answers

Page | 1



Illinois Class D Water License
Questions with Detailed Verified
Answers

Question: 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


Question:If the water level in tower 1 is 118 feet what will the pressure reading
be at the base
Answer: 51.1 psi


Question: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


Question:What is the first item used when installing a service line to a
customer?
Answer: Corporation stop


Question: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

, Page | 2

Question: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


Question:To isolate part of a distribution system what type of valve is
commonly used?
Answer: Gate valve


Question:Trihalomethanes (THMs) are caused by?
Answer: Reaction of chlorinated water with numeric materials found in
surface water sources


Question:The longer the contact time water and chlorine residuals enjoy the
________ the THM level will probably be
Answer: Higher


Question:THM's should be eliminated from finished water because they cause
?
Answer: Cancer


Question:The maximum contaminant level for THM's is?
Answer: .080 mg/l


Question: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

, Page | 3

Question: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


Question:What type of water main is most likely to become contaminated
from gasoline saturated soil
Answer: PVC


Question:What type of materials must not be used as backfill for water
mains?
Answer: Cinders


Question:Nitrate in levels above _________ mg/L can cause "blue baby"
disease
Answer: 10


Question: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


Question:A boil order should be issued for?
Answer: Until further notice


Question:Upon the issuance of a boil order the IEPA regional office should be
notified of the order because ________________?