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Water & Wastewater Operator (WPI/ABC Class I) — Practice Exam

WD quality: practice questions

Our Water/Wastewater Operator bank has 12 questions on this topic. Here are 5 of them with answers; the full mock exam draws from every topic, like the real one.

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Question 1 · Water Distribution Class I

What can red or brown water complaints indicate?

  1. Too much chlorine at the booster station
  2. Algae in the tank
  3. Too much chlorine being fed at the booster station
  4. Iron corrosion or disturbed sediment in mains
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D. Iron corrosion or disturbed sediment in mains — Flushing and corrosion control help.

Question 2 · Water Distribution Class I

What can cause loss of chlorine residual in remote parts of the system?

  1. Long water age, biofilm and pipe-wall reactions
  2. High residual at the plant
  3. Short water age and high residual leaving the plant
  4. Cold water only
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A. Long water age, biofilm and pipe-wall reactions — Water age is a listed parameter.

Question 3 · Water Distribution Class I

What is the MRDL for chlorine in the distribution system?

  1. 0.2 mg/L
  2. 1.0 mg/L
  3. 4.0 mg/L
  4. 10 mg/L
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C. 4.0 mg/L — Running annual average.

Question 4 · Water Distribution Class I

What must happen after a routine total coliform-positive sample?

  1. Flush the whole system and stop testing
  2. Nothing; one positive sample doesn't require any follow-up
  3. Repeat samples at and near the site, and test positive samples for E. coli
  4. Nothing; a single positive sample doesn't require any follow-up action at all
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C. Repeat samples at and near the site, and test positive samples for E. coli — RTCR repeat sampling.

Question 5 · Water Distribution Class I

How should chlorine cylinders at a booster station be stored?

  1. Near heat
  2. In the pump room with the motors
  3. Upright, chained, with caps on when not in use
  4. Lying loose on the floor near the pump motors so they stay warm
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C. Upright, chained, with caps on when not in use — Transport, store and feed chemicals safely.

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