REHS Exam: Water (questions and
answers) latest updated
Around what percent of Earth's water is freshwater? - correct answer ✔✔1-3%
What is the saturated zone? - correct answer ✔✔Underground region in which all
the earth's pores are filled with water
What is the water table? - correct answer ✔✔The level below which the ground is
saturated with water
What is the vadose zone? - correct answer ✔✔The unsaturated area above the
water table
What is an artesian well? - correct answer ✔✔A well drilled into an aquifer under
pressure, requiring no pumping to get water flow
What is an aquitard? - correct answer ✔✔Usually a layer of clay, soil, silt, or sand
that impedes the flow of water
What does the Safe Drinking Water Act (SDWA) consider a Public Water System
(PWS)? - correct answer ✔✔Water system that has at least 15 connections OR
regularly serves at least 25 people
, What is the difference between a community water system (CWS) and non-
community water system (NCWS)? - correct answer ✔✔NCWSs do not serve a
permanent resident population
All wells EXCEPT this type of well are regulated by the EPA - correct answer
✔✔Private wells
Which of the following is true regarding slow sand filtration?
a) Consists of small filter beds with fast filtration rates
b) Consists of large filter beds with slow filtration rates
c) Uses chemical coagulation
d) Does not reduce bacteria - correct answer ✔✔b) Consists of large filter beds
with slow filtration rates
In coagulation, finely dispersed solids (colloids), form large particles called
_________ when an electrical charge is passed through the medium. - correct
answer ✔✔floc
Larger flocs are removed by __________________ - correct answer
✔✔sedimentation
Quality of sanitary surveys is totally dependent on: - correct answer ✔✔the
quality of the surveyor
The 1974 Safe Drinking Water Act allows the EPA to enforce regulations called: -
correct answer ✔✔the National Primary Drinking Water Regulations
answers) latest updated
Around what percent of Earth's water is freshwater? - correct answer ✔✔1-3%
What is the saturated zone? - correct answer ✔✔Underground region in which all
the earth's pores are filled with water
What is the water table? - correct answer ✔✔The level below which the ground is
saturated with water
What is the vadose zone? - correct answer ✔✔The unsaturated area above the
water table
What is an artesian well? - correct answer ✔✔A well drilled into an aquifer under
pressure, requiring no pumping to get water flow
What is an aquitard? - correct answer ✔✔Usually a layer of clay, soil, silt, or sand
that impedes the flow of water
What does the Safe Drinking Water Act (SDWA) consider a Public Water System
(PWS)? - correct answer ✔✔Water system that has at least 15 connections OR
regularly serves at least 25 people
, What is the difference between a community water system (CWS) and non-
community water system (NCWS)? - correct answer ✔✔NCWSs do not serve a
permanent resident population
All wells EXCEPT this type of well are regulated by the EPA - correct answer
✔✔Private wells
Which of the following is true regarding slow sand filtration?
a) Consists of small filter beds with fast filtration rates
b) Consists of large filter beds with slow filtration rates
c) Uses chemical coagulation
d) Does not reduce bacteria - correct answer ✔✔b) Consists of large filter beds
with slow filtration rates
In coagulation, finely dispersed solids (colloids), form large particles called
_________ when an electrical charge is passed through the medium. - correct
answer ✔✔floc
Larger flocs are removed by __________________ - correct answer
✔✔sedimentation
Quality of sanitary surveys is totally dependent on: - correct answer ✔✔the
quality of the surveyor
The 1974 Safe Drinking Water Act allows the EPA to enforce regulations called: -
correct answer ✔✔the National Primary Drinking Water Regulations
