CA Water Treatment Operator Cert Exam T2
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Answers) Plus Rationales 2026 Q&A | Instant
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1. What is the primary purpose of coagulation in water treatment?
a) Disinfect water
b) Adjust pH
c) Remove turbidity
d) Add fluoride
c) Remove turbidity
Coagulation destabilizes suspended particles so they can aggregate and
be removed, reducing turbidity.
2. Which chemical is commonly used as a coagulant in water
treatment?
a) Sodium hypochlorite
b) Aluminum sulfate
c) Sodium fluoride
d) Calcium carbonate
b) Aluminum sulfate
Aluminum sulfate (alum) is widely used to destabilize colloidal particles
during coagulation.
3. What is the typical pH range for effective coagulation with alum?
a) 4.0 – 5.0
b) 5.5 – 7.0
, c) 7.5 – 9.0
d) 9.0 – 10.5
b) 5.5 – 7.0
Alum works best in slightly acidic to neutral water for optimum particle
destabilization.
4. Which process follows coagulation and flocculation in
conventional water treatment?
a) Filtration
b) Sedimentation
c) Chlorination
d) Fluoridation
b) Sedimentation
Sedimentation allows flocs to settle out of the water before filtration.
5. What type of filter media is most commonly used in slow sand
filters?
a) Gravel only
b) Anthracite
c) Sand
d) Activated carbon
c) Sand
Slow sand filters primarily use sand to trap and biologically degrade
impurities.
6. Which disinfection method is most effective against
Cryptosporidium?
a) Chlorination
b) Ozonation
, c) Ultraviolet (UV)
d) Fluoridation
c) Ultraviolet (UV)
Cryptosporidium is resistant to chlorine but can be inactivated by UV
light.
7. What is the maximum residual disinfectant level (MRDL) for
chlorine in drinking water under US regulations?
a) 1.0 mg/L
b) 2.0 mg/L
c) 4.0 mg/L
d) 10.0 mg/L
c) 4.0 mg/L
The EPA sets the MRDL for chlorine at 4 mg/L to ensure safety and
effectiveness.
8. What is the main purpose of pH adjustment in water treatment?
a) Control microbial growth
b) Improve taste
c) Optimize coagulation and prevent corrosion
d) Remove heavy metals
c) Optimize coagulation and prevent corrosion
Proper pH ensures effective chemical reactions and protects distribution
system integrity.
9. Which waterborne pathogen is most commonly associated with
giardiasis?
a) Giardia lamblia
b) Legionella pneumophila
, c) E. coli
d) Cryptosporidium
a) Giardia lamblia
Giardia is a protozoan parasite causing gastrointestinal illness, often in
untreated water.
10. What is the typical detention time in a conventional
sedimentation basin?
a) 5–15 minutes
b) 1–3 hours
c) 24 hours
d) 48 hours
b) 1–3 hours
Sedimentation basins allow flocs sufficient time to settle before
filtration.
11. What is the primary function of a rapid mix basin in water
treatment?
a) Remove bacteria
b) Rapidly disperse chemicals
c) Settle large particles
d) Filter water
b) Rapidly disperse chemicals
Rapid mixing ensures even distribution of coagulants before
flocculation.
12. What is the main byproduct of chlorine reacting with natural
organic matter?
a) Chloramine
Questions With Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A | Instant
Download Pdf
1. What is the primary purpose of coagulation in water treatment?
a) Disinfect water
b) Adjust pH
c) Remove turbidity
d) Add fluoride
c) Remove turbidity
Coagulation destabilizes suspended particles so they can aggregate and
be removed, reducing turbidity.
2. Which chemical is commonly used as a coagulant in water
treatment?
a) Sodium hypochlorite
b) Aluminum sulfate
c) Sodium fluoride
d) Calcium carbonate
b) Aluminum sulfate
Aluminum sulfate (alum) is widely used to destabilize colloidal particles
during coagulation.
3. What is the typical pH range for effective coagulation with alum?
a) 4.0 – 5.0
b) 5.5 – 7.0
, c) 7.5 – 9.0
d) 9.0 – 10.5
b) 5.5 – 7.0
Alum works best in slightly acidic to neutral water for optimum particle
destabilization.
4. Which process follows coagulation and flocculation in
conventional water treatment?
a) Filtration
b) Sedimentation
c) Chlorination
d) Fluoridation
b) Sedimentation
Sedimentation allows flocs to settle out of the water before filtration.
5. What type of filter media is most commonly used in slow sand
filters?
a) Gravel only
b) Anthracite
c) Sand
d) Activated carbon
c) Sand
Slow sand filters primarily use sand to trap and biologically degrade
impurities.
6. Which disinfection method is most effective against
Cryptosporidium?
a) Chlorination
b) Ozonation
, c) Ultraviolet (UV)
d) Fluoridation
c) Ultraviolet (UV)
Cryptosporidium is resistant to chlorine but can be inactivated by UV
light.
7. What is the maximum residual disinfectant level (MRDL) for
chlorine in drinking water under US regulations?
a) 1.0 mg/L
b) 2.0 mg/L
c) 4.0 mg/L
d) 10.0 mg/L
c) 4.0 mg/L
The EPA sets the MRDL for chlorine at 4 mg/L to ensure safety and
effectiveness.
8. What is the main purpose of pH adjustment in water treatment?
a) Control microbial growth
b) Improve taste
c) Optimize coagulation and prevent corrosion
d) Remove heavy metals
c) Optimize coagulation and prevent corrosion
Proper pH ensures effective chemical reactions and protects distribution
system integrity.
9. Which waterborne pathogen is most commonly associated with
giardiasis?
a) Giardia lamblia
b) Legionella pneumophila
, c) E. coli
d) Cryptosporidium
a) Giardia lamblia
Giardia is a protozoan parasite causing gastrointestinal illness, often in
untreated water.
10. What is the typical detention time in a conventional
sedimentation basin?
a) 5–15 minutes
b) 1–3 hours
c) 24 hours
d) 48 hours
b) 1–3 hours
Sedimentation basins allow flocs sufficient time to settle before
filtration.
11. What is the primary function of a rapid mix basin in water
treatment?
a) Remove bacteria
b) Rapidly disperse chemicals
c) Settle large particles
d) Filter water
b) Rapidly disperse chemicals
Rapid mixing ensures even distribution of coagulants before
flocculation.
12. What is the main byproduct of chlorine reacting with natural
organic matter?
a) Chloramine
