WATER DISTRIBUTION LEVEL 1 EXAM
2025/2026 LATEST QUESTIONS AND ANSWERS
GRADED A+
The minimum and maximum chloride residual in a water distribution system is ?
0.2 mg/l and 4mg/L of free chlorine
Nitrate may not exceed what concentration when tested yearly for a groundwater
treatment plant ?
10 mg/L
The minimum number of total coliform samples that must be collected per month
is based on Wich of the following ?
The population served by the system
When a distribution bacteriological sample is positive for a total coliform the
procedure is ?
Repeat the sample and take a sample 5 connections upstream and downstream to
confirm total coliform
,For lead and copper sample the water must be In the pipeline for at least?
6 hours
The chlorine dose added to water for disinfection is:
Demand plus residual
The sterilization of drinking water
is not necessary
Chlorine gas has what effect on the pH of water?
It lowers the pH
Disease causing bacteria are known as what?
Pathogenic
What is the recommended minimum contact time when disinfecting water mains
with the C12 slug method?
,3 hours
Depending on its concentration and length of exposure, which of the following
gases can cause lung and skin irritation?
Chlorine
What is hydraulic grade line ?
A line to which the water level would rise in a small ,vertical tube,connected to the
pipe
Alkalinity is expressed in:
mg/L of equivalent calcium carbonate
A pH of 6.7 would be considered:
Acidic
In high concentrations, calcium and magnesium cause:
, Hard water
Low water temperature has what effect on the density of water?
Increases the density
T or F: All bacteria under the Total Coliform group are pathogenic
False
1 multiple choice option
T or F: The P/A test method will allow you to quantify the number of organisms
per 100 mL of sample
False
1 multiple choice option
A positive to the Total Coliform test using the MPN method is indicated by:
Formation of gas bubbles
2025/2026 LATEST QUESTIONS AND ANSWERS
GRADED A+
The minimum and maximum chloride residual in a water distribution system is ?
0.2 mg/l and 4mg/L of free chlorine
Nitrate may not exceed what concentration when tested yearly for a groundwater
treatment plant ?
10 mg/L
The minimum number of total coliform samples that must be collected per month
is based on Wich of the following ?
The population served by the system
When a distribution bacteriological sample is positive for a total coliform the
procedure is ?
Repeat the sample and take a sample 5 connections upstream and downstream to
confirm total coliform
,For lead and copper sample the water must be In the pipeline for at least?
6 hours
The chlorine dose added to water for disinfection is:
Demand plus residual
The sterilization of drinking water
is not necessary
Chlorine gas has what effect on the pH of water?
It lowers the pH
Disease causing bacteria are known as what?
Pathogenic
What is the recommended minimum contact time when disinfecting water mains
with the C12 slug method?
,3 hours
Depending on its concentration and length of exposure, which of the following
gases can cause lung and skin irritation?
Chlorine
What is hydraulic grade line ?
A line to which the water level would rise in a small ,vertical tube,connected to the
pipe
Alkalinity is expressed in:
mg/L of equivalent calcium carbonate
A pH of 6.7 would be considered:
Acidic
In high concentrations, calcium and magnesium cause:
, Hard water
Low water temperature has what effect on the density of water?
Increases the density
T or F: All bacteria under the Total Coliform group are pathogenic
False
1 multiple choice option
T or F: The P/A test method will allow you to quantify the number of organisms
per 100 mL of sample
False
1 multiple choice option
A positive to the Total Coliform test using the MPN method is indicated by:
Formation of gas bubbles
