Indiana Water Treatment Operator Level I –
Practice Exam Questions And Correct Answers
(Verified Answers) Plus Rationales 2026 Q&A |
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1. The primary goal of coagulation in water treatment is to:
A. Increase pH
B. Reduce hardness
C. Destabilize particles
D. Remove dissolved gases
Answer: C
Coagulation neutralizes particle charges so they can clump and be
removed.
2. Alum is most effective within which pH range?
A. 2–4
B. 4–5
C. 5.5–7.5
D. 8–10
Answer: C
Alum forms optimal floc within a slightly acidic to neutral pH.
3. The purpose of flocculation is to:
A. Disinfect water
B. Form larger, settleable particles
C. Remove dissolved metals
D. Adjust alkalinity
, Answer: B
Flocculation gently mixes water to grow floc.
4. The most common disinfectant used in surface water treatment
plants is:
A. Ozone
B. UV light
C. Chloramines
D. Chlorine
Answer: D
Chlorine is widely used due to cost and residual properties.
5. The chlorine demand is the difference between the chlorine
added and the:
A. Free chlorine
B. Combined chlorine
C. Total chlorine
D. Chlorine residual
Answer: D
Demand represents chlorine consumed by reactions in the water.
6. The ideal turbidity level after filtration should generally be:
A. <5 NTU
B. <2 NTU
C. <1 NTU
D. <0.3 NTU
Answer: D
Regulations often require filtered water turbidity below 0.3 NTU.
7. A rapid sand filter typically has a filtration rate of:
A. 0.5 gpm/ft²
, B. 2–4 gpm/ft²
C. 5–10 gpm/ft²
D. 12–20 gpm/ft²
Answer: C
Rapid sand filters usually operate in this mid-range.
8. Backwashing a filter primarily removes:
A. Dissolved solids
B. Hardness
C. Accumulated floc
D. Pathogens
Answer: C
Backwashing flushes out trapped particulate matter.
9. A common indicator organism used to assess biological
contamination is:
A. Giardia
B. Cryptosporidium
C. E. coli
D. Salmonella
Answer: C
E. coli indicates fecal contamination.
10. Which chemical raises pH and alkalinity?
A. Sulfuric acid
B. Caustic soda
C. CO₂
D. Alum
Answer: B
Caustic soda increases both pH and alkalinity.
Practice Exam Questions And Correct Answers
(Verified Answers) Plus Rationales 2026 Q&A |
Instant Download Pdf
1. The primary goal of coagulation in water treatment is to:
A. Increase pH
B. Reduce hardness
C. Destabilize particles
D. Remove dissolved gases
Answer: C
Coagulation neutralizes particle charges so they can clump and be
removed.
2. Alum is most effective within which pH range?
A. 2–4
B. 4–5
C. 5.5–7.5
D. 8–10
Answer: C
Alum forms optimal floc within a slightly acidic to neutral pH.
3. The purpose of flocculation is to:
A. Disinfect water
B. Form larger, settleable particles
C. Remove dissolved metals
D. Adjust alkalinity
, Answer: B
Flocculation gently mixes water to grow floc.
4. The most common disinfectant used in surface water treatment
plants is:
A. Ozone
B. UV light
C. Chloramines
D. Chlorine
Answer: D
Chlorine is widely used due to cost and residual properties.
5. The chlorine demand is the difference between the chlorine
added and the:
A. Free chlorine
B. Combined chlorine
C. Total chlorine
D. Chlorine residual
Answer: D
Demand represents chlorine consumed by reactions in the water.
6. The ideal turbidity level after filtration should generally be:
A. <5 NTU
B. <2 NTU
C. <1 NTU
D. <0.3 NTU
Answer: D
Regulations often require filtered water turbidity below 0.3 NTU.
7. A rapid sand filter typically has a filtration rate of:
A. 0.5 gpm/ft²
, B. 2–4 gpm/ft²
C. 5–10 gpm/ft²
D. 12–20 gpm/ft²
Answer: C
Rapid sand filters usually operate in this mid-range.
8. Backwashing a filter primarily removes:
A. Dissolved solids
B. Hardness
C. Accumulated floc
D. Pathogens
Answer: C
Backwashing flushes out trapped particulate matter.
9. A common indicator organism used to assess biological
contamination is:
A. Giardia
B. Cryptosporidium
C. E. coli
D. Salmonella
Answer: C
E. coli indicates fecal contamination.
10. Which chemical raises pH and alkalinity?
A. Sulfuric acid
B. Caustic soda
C. CO₂
D. Alum
Answer: B
Caustic soda increases both pH and alkalinity.
