CALIFORNIA GRADE 1 WATER
TREATMENT OPERATOR
CERTIFICATION EXAM QUESTIONS
AND ANSWERS GRADED A+ 2026
What is one reason the chlorine demand would suddenly increase from 0.7 to 3.2 mg/L while
treating raw water from a well? - ANS A contaminant entered the aquifer
How will a decrease in water temperature affect the disinfecting action of chlorine? -
ANS The disinfection is less effective
Examples of protozoa that must be removed from drinking water to protect public health -
ANS Giardia and Cryptosporidium
How is water prevented from entering a gas chlorinator? - ANS A check valve
Of the following characteristics of raw water, the least likely to cause health issues in consumers
is ______? - ANS physical
What is the never-ending transmission of water from the Earth into the atmosphere and back
again? - ANS The Hydrologic Cycle
@COPYRIGHT 2026/2027 ALLRIGHTS RESERVED 1
,What fraction of the earth surface is covered with water? - ANS Three-Quarters (3/4)
What is the process by which water becomes a gas and rises? - ANS Evaporation
To deliberately form chloramines, a water supplier mixes chlorine gas with _____? -
ANS Ammonia (ammonia + chlorine = chloramines)
To remove a calcium scale deposit from the liquid head of a chemical feed pump, remove it,
then soak it in_____? - ANS A weak solution of hydrochloric acid
Why is turbidity in drinking water is considered undesirable? - ANS Because it necessitates
extensive treatment and produces greater amounts of sludge
What does HTH (high test hypochlorite), a dry white granular compound, contain? - ANS 65
to 70% chlorine
What is a non-halogenic oxidizing chemical that may be substituted for pre-chlorination to avoid
formation of DBP's? - ANS Potassium Permanganate
Which of the following forms the strongest disinfectant in solution? - ANS Dichloramines
The Colilert Method can detect the presence of both total and fecal coliforms after how many
hours of incubation? - ANS 18 to 24 hours
At what temperature is a fusible plug on a chlorine cylinder designed to melt and release
chlorine gas? - ANS 158 to 165°F
@COPYRIGHT 2026/2027 ALLRIGHTS RESERVED 2
, What alternative disinfectant is most commonly used to avoid the formation of THM's
(trihalomethanes) at larger water treatment plants? - ANS Ozone (oxygen)
What are the nutrients in water taken up by algae during sunlight periods? - ANS carbon,
nitrates, and ammonia
What is the moisture passing from trees and other plants into the atmosphere referred to as? -
ANS Evapotranspiration
What is capillary fringe? - ANS The porous material just above the water table which holds
small quantities of water by capillary action
What is the ground water table? - ANS The upper surface of the zone of saturation of
groundwater in a confined aquifer
Where can pure water be found? - ANS A laboratory
What is described as the universal solvent? - ANS Water
What primary sources of water do the hydrologic cycles create? - ANS Ground and Surface
Water
What is red water usually caused by? - ANS Iron
What forms in the mixing of precipitation and certain gases in the atmosphere? - ANS Acid
Rain
@COPYRIGHT 2026/2027 ALLRIGHTS RESERVED 3
TREATMENT OPERATOR
CERTIFICATION EXAM QUESTIONS
AND ANSWERS GRADED A+ 2026
What is one reason the chlorine demand would suddenly increase from 0.7 to 3.2 mg/L while
treating raw water from a well? - ANS A contaminant entered the aquifer
How will a decrease in water temperature affect the disinfecting action of chlorine? -
ANS The disinfection is less effective
Examples of protozoa that must be removed from drinking water to protect public health -
ANS Giardia and Cryptosporidium
How is water prevented from entering a gas chlorinator? - ANS A check valve
Of the following characteristics of raw water, the least likely to cause health issues in consumers
is ______? - ANS physical
What is the never-ending transmission of water from the Earth into the atmosphere and back
again? - ANS The Hydrologic Cycle
@COPYRIGHT 2026/2027 ALLRIGHTS RESERVED 1
,What fraction of the earth surface is covered with water? - ANS Three-Quarters (3/4)
What is the process by which water becomes a gas and rises? - ANS Evaporation
To deliberately form chloramines, a water supplier mixes chlorine gas with _____? -
ANS Ammonia (ammonia + chlorine = chloramines)
To remove a calcium scale deposit from the liquid head of a chemical feed pump, remove it,
then soak it in_____? - ANS A weak solution of hydrochloric acid
Why is turbidity in drinking water is considered undesirable? - ANS Because it necessitates
extensive treatment and produces greater amounts of sludge
What does HTH (high test hypochlorite), a dry white granular compound, contain? - ANS 65
to 70% chlorine
What is a non-halogenic oxidizing chemical that may be substituted for pre-chlorination to avoid
formation of DBP's? - ANS Potassium Permanganate
Which of the following forms the strongest disinfectant in solution? - ANS Dichloramines
The Colilert Method can detect the presence of both total and fecal coliforms after how many
hours of incubation? - ANS 18 to 24 hours
At what temperature is a fusible plug on a chlorine cylinder designed to melt and release
chlorine gas? - ANS 158 to 165°F
@COPYRIGHT 2026/2027 ALLRIGHTS RESERVED 2
, What alternative disinfectant is most commonly used to avoid the formation of THM's
(trihalomethanes) at larger water treatment plants? - ANS Ozone (oxygen)
What are the nutrients in water taken up by algae during sunlight periods? - ANS carbon,
nitrates, and ammonia
What is the moisture passing from trees and other plants into the atmosphere referred to as? -
ANS Evapotranspiration
What is capillary fringe? - ANS The porous material just above the water table which holds
small quantities of water by capillary action
What is the ground water table? - ANS The upper surface of the zone of saturation of
groundwater in a confined aquifer
Where can pure water be found? - ANS A laboratory
What is described as the universal solvent? - ANS Water
What primary sources of water do the hydrologic cycles create? - ANS Ground and Surface
Water
What is red water usually caused by? - ANS Iron
What forms in the mixing of precipitation and certain gases in the atmosphere? - ANS Acid
Rain
@COPYRIGHT 2026/2027 ALLRIGHTS RESERVED 3
