Water Distribution Operator Class 3 Latest 2026
Questions and Correct Detailed Answers Already
Graded A+
What is the MCL for alpha particles? - CORRECT ANSWER-15 pCi/L
What term refers to the highest level of a disinfectant allowed in drinking water? -
CORRECT ANSWER-Maximum residual disinfectant level (MRDL)
What is the MCL for arsenic? - CORRECT ANSWER-10 ug/L
The pressure during fire flow conditions should not drop below - CORRECT
ANSWER-20 psi
which type of distribution system configuration has smaller mains that generally
terminate at dead ends? - CORRECT ANSWER-Tree system
How many times higher than the normal operating pressure should the pressure
rating of distribution system piping be? - CORRECT ANSWER-2.5-4.0 times
,Regarding fire flow, mains smaller than 6 in. should be used only - CORRECT
ANSWER-to complete a grid
What is the commonly accepted water velocity in water mains at maximum
flows? - CORRECT ANSWER-2-4 ft/sec
If a water system collects 40 samples per month for the analysis of total coliforms,
what percentage of total coliform positive samples are acceptable for the system
to remain in compliance with the maximum contaminant level for total coliforms?
- CORRECT ANSWER-No more than 5%
Water systems are required to achieve at least ____ removal and/or inactivation
of viruses between a point where the raw water is not subject to the
recontamination by surface water runoff and a point downstream before or at the
first customer. - CORRECT ANSWER-4 log
Continuous chlorine residual monitoring is required where the water enters the
distribution system under the Surface Water Treatment Rule when the -
CORRECT ANSWER-population served is >3,300 people
A community water system must post the Consumer Confidence Report on a
publicly accessible website if it serves more than - CORRECT ANSWER-100,000
,Public water systems that cannot meet the required removal of total organic
compounds (TOCs) can comply if the source-water TOC level is _____, calculated
quarterly as a running annual average. - CORRECT ANSWER-<2.0 mg/L
The Surface Water Treatment Rule does not specify which of the following
treatment technology? - CORRECT ANSWER-chloramine disinfection
A regulated organic contaminant concentration that exceeds the MCL -
CORRECT ANSWER-is a Tier 2 violation requiring public notification within 30
days
Operators must balance satisfying regulations on the amount of certain
chlorinated organic compounds with - CORRECT ANSWER-meeting disinfection
limits
A water system using conventional filtration treatment does not have to use
enhanced coagulation to achieve the total organic carbon (TOC) percent removal
if - CORRECT ANSWER-the treated water quarterly running average TOC is less
than 2.0 mg/L
Regulations that govern US water supply and treatment are developed by the US
EPA under what act? - CORRECT ANSWER-Safe Drinking Water Act (SDWA)
, What is the MCL goal for copper? - CORRECT ANSWER-1.3 mg/L
The size and capacity of a water distribution system is based largely on -
CORRECT ANSWER-fire demand
A(n) ____ layout centers around a single arterial main, which decreases in size
with length - CORRECT ANSWER-tree system
What type of water system uses wells, springs, or infiltration galleries as its source
of supply? - CORRECT ANSWER-groundwater system
What type of water system is established to serve widely spaced homes and
communities in areas having no available groundwater or having water of very
poor quality? - CORRECT ANSWER-rural water system
In what type of water distribution layout are all ends of the mains connected to
eliminated dead ends? - CORRECT ANSWER-grid system
What is the term for the water use during the 24 hours of highest demand during
the year? - CORRECT ANSWER-maximum day demand
Questions and Correct Detailed Answers Already
Graded A+
What is the MCL for alpha particles? - CORRECT ANSWER-15 pCi/L
What term refers to the highest level of a disinfectant allowed in drinking water? -
CORRECT ANSWER-Maximum residual disinfectant level (MRDL)
What is the MCL for arsenic? - CORRECT ANSWER-10 ug/L
The pressure during fire flow conditions should not drop below - CORRECT
ANSWER-20 psi
which type of distribution system configuration has smaller mains that generally
terminate at dead ends? - CORRECT ANSWER-Tree system
How many times higher than the normal operating pressure should the pressure
rating of distribution system piping be? - CORRECT ANSWER-2.5-4.0 times
,Regarding fire flow, mains smaller than 6 in. should be used only - CORRECT
ANSWER-to complete a grid
What is the commonly accepted water velocity in water mains at maximum
flows? - CORRECT ANSWER-2-4 ft/sec
If a water system collects 40 samples per month for the analysis of total coliforms,
what percentage of total coliform positive samples are acceptable for the system
to remain in compliance with the maximum contaminant level for total coliforms?
- CORRECT ANSWER-No more than 5%
Water systems are required to achieve at least ____ removal and/or inactivation
of viruses between a point where the raw water is not subject to the
recontamination by surface water runoff and a point downstream before or at the
first customer. - CORRECT ANSWER-4 log
Continuous chlorine residual monitoring is required where the water enters the
distribution system under the Surface Water Treatment Rule when the -
CORRECT ANSWER-population served is >3,300 people
A community water system must post the Consumer Confidence Report on a
publicly accessible website if it serves more than - CORRECT ANSWER-100,000
,Public water systems that cannot meet the required removal of total organic
compounds (TOCs) can comply if the source-water TOC level is _____, calculated
quarterly as a running annual average. - CORRECT ANSWER-<2.0 mg/L
The Surface Water Treatment Rule does not specify which of the following
treatment technology? - CORRECT ANSWER-chloramine disinfection
A regulated organic contaminant concentration that exceeds the MCL -
CORRECT ANSWER-is a Tier 2 violation requiring public notification within 30
days
Operators must balance satisfying regulations on the amount of certain
chlorinated organic compounds with - CORRECT ANSWER-meeting disinfection
limits
A water system using conventional filtration treatment does not have to use
enhanced coagulation to achieve the total organic carbon (TOC) percent removal
if - CORRECT ANSWER-the treated water quarterly running average TOC is less
than 2.0 mg/L
Regulations that govern US water supply and treatment are developed by the US
EPA under what act? - CORRECT ANSWER-Safe Drinking Water Act (SDWA)
, What is the MCL goal for copper? - CORRECT ANSWER-1.3 mg/L
The size and capacity of a water distribution system is based largely on -
CORRECT ANSWER-fire demand
A(n) ____ layout centers around a single arterial main, which decreases in size
with length - CORRECT ANSWER-tree system
What type of water system uses wells, springs, or infiltration galleries as its source
of supply? - CORRECT ANSWER-groundwater system
What type of water system is established to serve widely spaced homes and
communities in areas having no available groundwater or having water of very
poor quality? - CORRECT ANSWER-rural water system
In what type of water distribution layout are all ends of the mains connected to
eliminated dead ends? - CORRECT ANSWER-grid system
What is the term for the water use during the 24 hours of highest demand during
the year? - CORRECT ANSWER-maximum day demand
