AWWA ABC WATER DISTRIBUTION GRADES 1 & 2 EXAM
QUESTIONS WITH CORRECT ANSWERS 2025/2026
Which agency sets legal limits on the concentration levels of harmful contaminants in potable
water distributed to customers? - CORRECT ANSWER -US Environmental Protection Agency
The number of monthly distributions system bacteriologiacal samples required is - CORRECT
ANSWER -Based on the population served
What is the maximum contaminant level for total trihalomethanes (TTHM) in the united States?
- CORRECT ANSWER -0.080 mg/L
Under the Surface Water Treatment Rule, disinfection residuals must be collected at the same
location in the distribution system as - CORRECT ANSWER -coliform samples
Iron can cause "red water" and thus customer complaints when its concentration is above its
secondary maximum contaminant level of - CORRECT ANSWER -0.30 mg/L
The goal of the Surface Drinking Water Act is for each ________ to accept primary enforcement
responsibility (primacy) for the operation of the state's drinking water program. - CORRECT
ANSWER -State
What is the objective of Total Coliform Rule? - CORRECT ANSWER -To promote routine
surveillance of distribution system water quality to search for fecal matter and/or disease-
causing bacteria
Which agency sets standards on the concentration levels of harmful contaminants in drinking
water? - CORRECT ANSWER -EPA
,Explain the difference between the different tiers of violations. Which tier is the most serious? -
CORRECT ANSWER -Tier 1 = 24 hours (most severe)
Tier 2= 30 days
Tier 3= 1 year
A positive E. Coli test must be reported to the primacy health agency within what time period? -
CORRECT ANSWER -24 hours
How is the required number of monthly bacteriological samples determined? - CORRECT
ANSWER -Population served
What is the action level for lead in first-draw samples taken from customer taps? - CORRECT
ANSWER -0.015 mg/L
A water system is designated a community public water system if it serves how many homes? -
CORRECT ANSWER -15 or more
What authority provides specific water sampling instructions? - CORRECT ANSWER -The state
primacy agency
According to the Lead and Copper Rule, what is the action level for lead? - CORRECT ANSWER -
0.015 mg/L
Head is measured in - CORRECT ANSWER -Feet
A plat is - CORRECT ANSWER -a map
, At which time of the day is the age of the water stored in the distribution system the highest? -
CORRECT ANSWER -Early morning
Water mains should primarily be sized based on - CORRECT ANSWER -adequate fire flow at an
appropriate pressure
The most desirable residential pressure ranges from - CORRECT ANSWER -50 to 75 psi (345 to
517kPa)
Domestic water use includes water that is supplied to residential areas, ____________, and
institutional facilities. - CORRECT ANSWER -commercial districts
Riparian doctrine is sometimes called the "rule of - CORRECT ANSWER -reasonable sharing."
During which season is water typically the highest? - CORRECT ANSWER -summer
Of the common types of distribution system, which type is considered least desirable? -
CORRECT ANSWER -Tree system
The velocity of water is calculated as the quantity of water that flows through a pipe - CORRECT
ANSWER -divided by the cross-sectional area of pipe
What is the term for water pressure in a main or in a container that is measured by a gauge? -
CORRECT ANSWER -Gage pressure
In hydraulics, how is head expressed? - CORRECT ANSWER -ft-pounds per pound
QUESTIONS WITH CORRECT ANSWERS 2025/2026
Which agency sets legal limits on the concentration levels of harmful contaminants in potable
water distributed to customers? - CORRECT ANSWER -US Environmental Protection Agency
The number of monthly distributions system bacteriologiacal samples required is - CORRECT
ANSWER -Based on the population served
What is the maximum contaminant level for total trihalomethanes (TTHM) in the united States?
- CORRECT ANSWER -0.080 mg/L
Under the Surface Water Treatment Rule, disinfection residuals must be collected at the same
location in the distribution system as - CORRECT ANSWER -coliform samples
Iron can cause "red water" and thus customer complaints when its concentration is above its
secondary maximum contaminant level of - CORRECT ANSWER -0.30 mg/L
The goal of the Surface Drinking Water Act is for each ________ to accept primary enforcement
responsibility (primacy) for the operation of the state's drinking water program. - CORRECT
ANSWER -State
What is the objective of Total Coliform Rule? - CORRECT ANSWER -To promote routine
surveillance of distribution system water quality to search for fecal matter and/or disease-
causing bacteria
Which agency sets standards on the concentration levels of harmful contaminants in drinking
water? - CORRECT ANSWER -EPA
,Explain the difference between the different tiers of violations. Which tier is the most serious? -
CORRECT ANSWER -Tier 1 = 24 hours (most severe)
Tier 2= 30 days
Tier 3= 1 year
A positive E. Coli test must be reported to the primacy health agency within what time period? -
CORRECT ANSWER -24 hours
How is the required number of monthly bacteriological samples determined? - CORRECT
ANSWER -Population served
What is the action level for lead in first-draw samples taken from customer taps? - CORRECT
ANSWER -0.015 mg/L
A water system is designated a community public water system if it serves how many homes? -
CORRECT ANSWER -15 or more
What authority provides specific water sampling instructions? - CORRECT ANSWER -The state
primacy agency
According to the Lead and Copper Rule, what is the action level for lead? - CORRECT ANSWER -
0.015 mg/L
Head is measured in - CORRECT ANSWER -Feet
A plat is - CORRECT ANSWER -a map
, At which time of the day is the age of the water stored in the distribution system the highest? -
CORRECT ANSWER -Early morning
Water mains should primarily be sized based on - CORRECT ANSWER -adequate fire flow at an
appropriate pressure
The most desirable residential pressure ranges from - CORRECT ANSWER -50 to 75 psi (345 to
517kPa)
Domestic water use includes water that is supplied to residential areas, ____________, and
institutional facilities. - CORRECT ANSWER -commercial districts
Riparian doctrine is sometimes called the "rule of - CORRECT ANSWER -reasonable sharing."
During which season is water typically the highest? - CORRECT ANSWER -summer
Of the common types of distribution system, which type is considered least desirable? -
CORRECT ANSWER -Tree system
The velocity of water is calculated as the quantity of water that flows through a pipe - CORRECT
ANSWER -divided by the cross-sectional area of pipe
What is the term for water pressure in a main or in a container that is measured by a gauge? -
CORRECT ANSWER -Gage pressure
In hydraulics, how is head expressed? - CORRECT ANSWER -ft-pounds per pound
