REHS MAIN EXAMINATION 2026 SET QUESTIONS AND
ANSWERS RATED A+
✔✔Which of the following would not contribute to water hardness?
a. calcium sulfate
b. magnesium sulfate
c. calcium chloride
d. sodium chloride - ✔✔sodium chloride
✔✔Improperly located wells, allowing fecal pollution of the water supply may lead to
outbreaks of:
a. botulism, leptospirosis, typhus fever, maria
b. brucellosis, strep infections, chlorea, yellow fever
c. salmonellosis, shigellosis, chlorea, hepatitis
d. relapsing fever, histoplasmosis, psittacosis - ✔✔salmonellosis, shigellosis, chlorea,
hepatitis
✔✔Historically in the US, most of the impetus for adequate water treatment came from
the need to control:
a. infectious hepatitis
b. tuberculosis
c. malaria
d. typhoid - ✔✔typhoid
✔✔The liquid form of chlorine used for emergency disinfection of small volumes of
a. calcium hypochlorite
b. sodium hypochlorite
c. bromide hypochlorite
d. potassium hypochlorite - ✔✔sodium hypochlorite
✔✔The presumptive evidence of the presence of coliform in the MPN test is:
a. the color change in the culture media
b. turbidity of the culture broth
c. the presence of gas from the fermentation of the media
d. metallic sheen of colonies - ✔✔the presence of gas from the fermentation of the
media
✔✔If hard water is softened by the ion exchange method, which one of the following will
increase?
,a. dissolved oxygen
b. iron
c. p1-1
d. sodium - ✔✔sodium
✔✔The langelier index is used to determine the point of stability of
a. aluminum sulfate
b. calcium carbonate
c. water pH
d. HOCL - ✔✔calcium carbonate
✔✔The manner in which water moves from place to place, changing from one form to
another is called the:
a. evaporation cycle
b. hydrologic cycle
c. precipitation cycle
d. evapotranspiration cycle - ✔✔hydrologic cycle
✔✔Which of the following is not a characteristic of groundwater?
a. most bacteria are absent
b. evaporation is virtually non-existent
c. it is less expensive to treat than surface water
d. it is more expensive to access than surface water - ✔✔it is more expensive to access
than surface water
✔✔The amendments of the Safe Drinking Water Act do not cover:
a. municipal wells
b. county reservoirs
c. private wells
d. public water systems - ✔✔private wells
✔✔Degradation of groundwater supplied by human-generated pollutants is generally
the result of:
a. failure to cover the water supply
b. failure to adequately chlorinate the water
c. faulty waste disposal practices
d. allowing industry exceptions to safe water practices - ✔✔faulty waste disposal
practices
,✔✔The primary reason for the decline in the water table in some groundwater
dependent areas of the world is:
a. over pumping
b. lack of permeable aquifers
c. high rate of evaporation
d. low rates of precipitation - ✔✔over pumping
✔✔Xeriscape landscaping means:
a. using rock as the basis for yard landscapes
b. eliminating the use of trees in yards for landscaping
c. selecting plants that can thrive on natural precipitation
d. using sand as the basis for all landscaping needs - ✔✔selecting plants that can thrive
on natural precipitation
✔✔Chemicals that have been used for pools disinfection include chlorine, chloro-iso-
cyanurates, bromine and
a. ammonia
b. soda ash
c. sodium thiosulfate
d. iodine - ✔✔iodine
✔✔The gutters or skimmers receive a minimum of ________ of the total pool water due
to the large quantity of organisms and materials which typically float.
a. 95%
b. 45%
c. 60%
d. 30% - ✔✔60%
✔✔To raise the pH, add
a. chlorine
b. muriatic acid
c. soda ash (sodium carbonate)
d. sulfuric acid - ✔✔soda ash (sodium carbonate)
✔✔A chemical commonly used to improve water clarity is
a. alum
b. muriatic acid
c. hydrogen chloride
d. sodium carbonate - ✔✔alum
, ✔✔When chlorine is added to water
a. one acid is formed
b. two acids are formed
c. HCl is considered the primary product
d. ozone is produced in large quantities - ✔✔one acid is formed
✔✔Which of the following would not be as likely to be contracted bathing at a beach?
a. leptospirosis
b. middle ear infection
c. spinal meningitis
d. all of the above - ✔✔spinal meningitis
✔✔The causative agent Naegleria fowleri has been linked to which of the following
diseases?
a. bacterial meningitis
b. PAM (primary amoebic meningoencephalitis)
c. cholera
d. diptheria - ✔✔PAM
✔✔A seechi disk is used to determine;
a. pH
b. clarity in recreational waters
c. coliform contamination
d. heavy metals - ✔✔clarity in recreational waters
✔✔A chemical used to adjust pool alkalinity is:
a. chlorine
b. calcium chloride
c. sodium bicarbonate
d. copper sulfate - ✔✔sodium bicarbonate
✔✔Which raises the pH of pool water?
a. chlorine
b. alum
c. sodium carbonate
d. all - ✔✔sodium carbonate
ANSWERS RATED A+
✔✔Which of the following would not contribute to water hardness?
a. calcium sulfate
b. magnesium sulfate
c. calcium chloride
d. sodium chloride - ✔✔sodium chloride
✔✔Improperly located wells, allowing fecal pollution of the water supply may lead to
outbreaks of:
a. botulism, leptospirosis, typhus fever, maria
b. brucellosis, strep infections, chlorea, yellow fever
c. salmonellosis, shigellosis, chlorea, hepatitis
d. relapsing fever, histoplasmosis, psittacosis - ✔✔salmonellosis, shigellosis, chlorea,
hepatitis
✔✔Historically in the US, most of the impetus for adequate water treatment came from
the need to control:
a. infectious hepatitis
b. tuberculosis
c. malaria
d. typhoid - ✔✔typhoid
✔✔The liquid form of chlorine used for emergency disinfection of small volumes of
a. calcium hypochlorite
b. sodium hypochlorite
c. bromide hypochlorite
d. potassium hypochlorite - ✔✔sodium hypochlorite
✔✔The presumptive evidence of the presence of coliform in the MPN test is:
a. the color change in the culture media
b. turbidity of the culture broth
c. the presence of gas from the fermentation of the media
d. metallic sheen of colonies - ✔✔the presence of gas from the fermentation of the
media
✔✔If hard water is softened by the ion exchange method, which one of the following will
increase?
,a. dissolved oxygen
b. iron
c. p1-1
d. sodium - ✔✔sodium
✔✔The langelier index is used to determine the point of stability of
a. aluminum sulfate
b. calcium carbonate
c. water pH
d. HOCL - ✔✔calcium carbonate
✔✔The manner in which water moves from place to place, changing from one form to
another is called the:
a. evaporation cycle
b. hydrologic cycle
c. precipitation cycle
d. evapotranspiration cycle - ✔✔hydrologic cycle
✔✔Which of the following is not a characteristic of groundwater?
a. most bacteria are absent
b. evaporation is virtually non-existent
c. it is less expensive to treat than surface water
d. it is more expensive to access than surface water - ✔✔it is more expensive to access
than surface water
✔✔The amendments of the Safe Drinking Water Act do not cover:
a. municipal wells
b. county reservoirs
c. private wells
d. public water systems - ✔✔private wells
✔✔Degradation of groundwater supplied by human-generated pollutants is generally
the result of:
a. failure to cover the water supply
b. failure to adequately chlorinate the water
c. faulty waste disposal practices
d. allowing industry exceptions to safe water practices - ✔✔faulty waste disposal
practices
,✔✔The primary reason for the decline in the water table in some groundwater
dependent areas of the world is:
a. over pumping
b. lack of permeable aquifers
c. high rate of evaporation
d. low rates of precipitation - ✔✔over pumping
✔✔Xeriscape landscaping means:
a. using rock as the basis for yard landscapes
b. eliminating the use of trees in yards for landscaping
c. selecting plants that can thrive on natural precipitation
d. using sand as the basis for all landscaping needs - ✔✔selecting plants that can thrive
on natural precipitation
✔✔Chemicals that have been used for pools disinfection include chlorine, chloro-iso-
cyanurates, bromine and
a. ammonia
b. soda ash
c. sodium thiosulfate
d. iodine - ✔✔iodine
✔✔The gutters or skimmers receive a minimum of ________ of the total pool water due
to the large quantity of organisms and materials which typically float.
a. 95%
b. 45%
c. 60%
d. 30% - ✔✔60%
✔✔To raise the pH, add
a. chlorine
b. muriatic acid
c. soda ash (sodium carbonate)
d. sulfuric acid - ✔✔soda ash (sodium carbonate)
✔✔A chemical commonly used to improve water clarity is
a. alum
b. muriatic acid
c. hydrogen chloride
d. sodium carbonate - ✔✔alum
, ✔✔When chlorine is added to water
a. one acid is formed
b. two acids are formed
c. HCl is considered the primary product
d. ozone is produced in large quantities - ✔✔one acid is formed
✔✔Which of the following would not be as likely to be contracted bathing at a beach?
a. leptospirosis
b. middle ear infection
c. spinal meningitis
d. all of the above - ✔✔spinal meningitis
✔✔The causative agent Naegleria fowleri has been linked to which of the following
diseases?
a. bacterial meningitis
b. PAM (primary amoebic meningoencephalitis)
c. cholera
d. diptheria - ✔✔PAM
✔✔A seechi disk is used to determine;
a. pH
b. clarity in recreational waters
c. coliform contamination
d. heavy metals - ✔✔clarity in recreational waters
✔✔A chemical used to adjust pool alkalinity is:
a. chlorine
b. calcium chloride
c. sodium bicarbonate
d. copper sulfate - ✔✔sodium bicarbonate
✔✔Which raises the pH of pool water?
a. chlorine
b. alum
c. sodium carbonate
d. all - ✔✔sodium carbonate
