Water Treatment Operator Certification
Comprehensive Resource To Help You Ace 2026-2027
Includes Frequently Tested Questions With ELABORATED
100% Correct COMPLETE SOLUTIONS
Guaranteed Pass First Attempt!!
Current Update!!
1. What is the method to remove calcium scale deposits from a chemical feed pump? -
Correct Answer: Soak it in a weak solution of hydrochloric acid (HCl) until the scale
softens, then rinse with tap water.
2. Why is turbidity in drinking water considered undesirable? - Correct Answer: It
provides a medium for waterborne transmission of pathogenic diseases, reduces the
effectiveness of chlorine, and can make drinking water cloudy.
3. What is HTH chlorine? - Correct Answer: HTH chlorine is a dry, white granular form
of hypochlorite that contains approximately 65% to 70% chlorine.
4. What oxidizing chemical may be used for pre-chlorination to avoid THM formation? -
Correct Answer: Potassium permanganate.
5. What is the incubation time for the Colilert method to detect coliforms? - Correct
Answer: 24.0 hours.
6. At what temperature do fusible plugs on a chlorine cylinder release gas? - Correct
Answer: The plugs will generally release gas at 120°F.
,7. What alternative disinfectant is commonly used to avoid THM formation at large plants?
- Correct Answer: Ozone gas.
8. What are the three most common nutrients in water taken up by algae? - Correct
Answer: Carbon, nitrogen, and phosphates.
9. When should the minimum number of bacteriological samples be collected? -
Correct Answer: On the same date of the month.
10. What should be done after a positive bacteriological sample? - Correct Answer: Re-
sample at the same site where the positive sample resulted and take five additional
samples both upstream and downstream.
11. On what basis are water treatment chemicals added to raw water? - Correct Answer:
Weight.
12. What are the most commonly used coagulants in water treatment? - Correct
Answer: Aluminum sulfate, ferric chloride, and cationic polymer.
13. To what depth can algae generally be found in a freshwater reservoir? - Correct
Answer: 12.0 ft.
14. What methods can be used to determine water hardness? - Correct Answer: The
EDTA titration method and atomic adsorption.
15. What is the optimum pH range for ferric chloride? - Correct Answer: 5.0 to 7.0.
,16. What are anionic, cationic, and nonionic chemicals also known as? - Correct Answer:
Polyelectrolytes.
17. What is the significance of mixing devices in water treatment? - Correct Answer:
They properly agitate to mix and allow time for reactions and to keep material in
suspension.
18. What has replaced the older rule of '30 minutes of contact time'? - Correct Answer:
The calculation of C t values.
19. What are the most favorable raw water conditions for good flocculation? - Correct
Answer: High pH and high alkalinity.
20. What is the minimum number of flocculation basins a plant should have? - Correct
Answer: No minimum number has been set.
21. What is agglomeration in water treatment? - Correct Answer: The gathering of
dispersed suspended matter into larger flocs and particles.
22. What changes should be considered if there are problems with floc formation? -
Correct Answer: Adjust coagulant dosage, change coagulant, or adjust flocculator mixing
intensity.
23. Where in a water treatment plant are polymers used to improve efficiency? - Correct
Answer: In the flash mix and flocculation tanks.
24. What process change is required if turbidity in raw water decreases from 8 to 2 NTUs? -
Correct Answer: No change is required.
, 25. What is Cryptosporidium? - Correct Answer: A microscopic parasite that causes
diarrhea if swallowed, found in almost all surface waters, and its infectious oocysts are
very resistant to disinfectant efforts.
26. What is the laboratory test to estimate optimum chemical dosage called? - Correct
Answer: Jar test.
27. What are finely divided solids that will not settle on their own called? - Correct
Answer: Colloids.
28. What form does Cryptosporidium exist as? - Correct Answer: Cyst.
29. What process is most effective for color removal in surface water plants? - Correct
Answer: Coagulation / flocculation.
30. What factors affect particle settling? - Correct Answer: Particle size and distribution,
shape of the particles, and density of the particles.
31. What are possible pump suction problems? - Correct Answer: Pump fails to prime,
suction line only partially filled with water, suction lift is too high, or inlet valve is
partially closed.
32. What is the most destructive type of pump cavitation? - Correct Answer: Suction, or
eye cavitation.
33. When do turbidity levels settle more quickly in a sedimentation basin? - Correct
Answer: When chemicals are dispensed in the sludge zone.
Comprehensive Resource To Help You Ace 2026-2027
Includes Frequently Tested Questions With ELABORATED
100% Correct COMPLETE SOLUTIONS
Guaranteed Pass First Attempt!!
Current Update!!
1. What is the method to remove calcium scale deposits from a chemical feed pump? -
Correct Answer: Soak it in a weak solution of hydrochloric acid (HCl) until the scale
softens, then rinse with tap water.
2. Why is turbidity in drinking water considered undesirable? - Correct Answer: It
provides a medium for waterborne transmission of pathogenic diseases, reduces the
effectiveness of chlorine, and can make drinking water cloudy.
3. What is HTH chlorine? - Correct Answer: HTH chlorine is a dry, white granular form
of hypochlorite that contains approximately 65% to 70% chlorine.
4. What oxidizing chemical may be used for pre-chlorination to avoid THM formation? -
Correct Answer: Potassium permanganate.
5. What is the incubation time for the Colilert method to detect coliforms? - Correct
Answer: 24.0 hours.
6. At what temperature do fusible plugs on a chlorine cylinder release gas? - Correct
Answer: The plugs will generally release gas at 120°F.
,7. What alternative disinfectant is commonly used to avoid THM formation at large plants?
- Correct Answer: Ozone gas.
8. What are the three most common nutrients in water taken up by algae? - Correct
Answer: Carbon, nitrogen, and phosphates.
9. When should the minimum number of bacteriological samples be collected? -
Correct Answer: On the same date of the month.
10. What should be done after a positive bacteriological sample? - Correct Answer: Re-
sample at the same site where the positive sample resulted and take five additional
samples both upstream and downstream.
11. On what basis are water treatment chemicals added to raw water? - Correct Answer:
Weight.
12. What are the most commonly used coagulants in water treatment? - Correct
Answer: Aluminum sulfate, ferric chloride, and cationic polymer.
13. To what depth can algae generally be found in a freshwater reservoir? - Correct
Answer: 12.0 ft.
14. What methods can be used to determine water hardness? - Correct Answer: The
EDTA titration method and atomic adsorption.
15. What is the optimum pH range for ferric chloride? - Correct Answer: 5.0 to 7.0.
,16. What are anionic, cationic, and nonionic chemicals also known as? - Correct Answer:
Polyelectrolytes.
17. What is the significance of mixing devices in water treatment? - Correct Answer:
They properly agitate to mix and allow time for reactions and to keep material in
suspension.
18. What has replaced the older rule of '30 minutes of contact time'? - Correct Answer:
The calculation of C t values.
19. What are the most favorable raw water conditions for good flocculation? - Correct
Answer: High pH and high alkalinity.
20. What is the minimum number of flocculation basins a plant should have? - Correct
Answer: No minimum number has been set.
21. What is agglomeration in water treatment? - Correct Answer: The gathering of
dispersed suspended matter into larger flocs and particles.
22. What changes should be considered if there are problems with floc formation? -
Correct Answer: Adjust coagulant dosage, change coagulant, or adjust flocculator mixing
intensity.
23. Where in a water treatment plant are polymers used to improve efficiency? - Correct
Answer: In the flash mix and flocculation tanks.
24. What process change is required if turbidity in raw water decreases from 8 to 2 NTUs? -
Correct Answer: No change is required.
, 25. What is Cryptosporidium? - Correct Answer: A microscopic parasite that causes
diarrhea if swallowed, found in almost all surface waters, and its infectious oocysts are
very resistant to disinfectant efforts.
26. What is the laboratory test to estimate optimum chemical dosage called? - Correct
Answer: Jar test.
27. What are finely divided solids that will not settle on their own called? - Correct
Answer: Colloids.
28. What form does Cryptosporidium exist as? - Correct Answer: Cyst.
29. What process is most effective for color removal in surface water plants? - Correct
Answer: Coagulation / flocculation.
30. What factors affect particle settling? - Correct Answer: Particle size and distribution,
shape of the particles, and density of the particles.
31. What are possible pump suction problems? - Correct Answer: Pump fails to prime,
suction line only partially filled with water, suction lift is too high, or inlet valve is
partially closed.
32. What is the most destructive type of pump cavitation? - Correct Answer: Suction, or
eye cavitation.
33. When do turbidity levels settle more quickly in a sedimentation basin? - Correct
Answer: When chemicals are dispensed in the sludge zone.
