Water Distribution Operator Practice Exams 1 2023/24

What is static head? A. The total equivalent height that a pump lifts water, including friction loss B. Friction loss C. The vertical distance between a reference point to the water surface, when the water is not moving. D. The horizontal distance between a reference point to the water surface - ANSWER-C. The vertical distance between a reference point to the water surface, when the water is not moving. If at least 40 samples per month are collected from a public water system , what is the minimum percentage of routine / repeat samples that must test negative for total coliform ? A. 80% B. 95% C. 85% D. 90% - ANSWER-B. 95% If the water has low pH , what does it indicate ? A. Corrosive water B. Hard water C. Scaling is a problem D. Ammonia is very high in concentration - ANSWER-A. Corrosive water What is the purpose of a mechanical seal ? A. Transmits input power from the driver to the impeller B. Increases the pressure of the liquid C. Prevents water leakage from the pump D. Supports the weight of the shaft assembly - ANSWER-C. Prevents water leakage from the pump What could cause a chlorine gas cylinder to frost ? A. Feed rate is too low B. pH of the water is too high C. pH of the water is too low D. Feed rate is too high - ANSWER-A. Feed rate is too high Which chemicals are formed when chlorine gas is injected into water ? A. Carbon dioxide and calcium hypochlorite B. Hypochlorous acid and hydrochloric acid C. Ammonia and sodium chloride D. Ozone and chlorine dioxide - ANSWER-B. Hypochlorous acid and hydrochloric acid Which of the following is true about the effectiveness of chlorine ? A. The higher the pH, the better the disinfection with chlorine. B. Chlorine is the most effective at pH=10. C. The lower the pH, the better the disinfection with chlorine. D. Chlorine is the most effective at pH = 12. - ANSWER-C. The lower the pH , the better the disinfection with chlorine . What does a high C factor for a pipe indicate ? A. Smooth pipe interior B. Very rough pipe interior C. Strong pipe D. The pipe is very resistant to corrosion - ANSWER-A. Smooth pipe interior What is the disadvantage of having a tree formation in the water distribution system ? A. Lack of dead-end mains makes it difficult to flush B. It is always more expensive to build than a grid system C. Fire hydrants are never installed when a water distribution system is built in a tree layout D. Dead-end mains - ANSWER-D. Dead-end mains If chlorine is injected into cold water , how would the cold temperature affect the effectiveness of chlorine ? A. Less contact time would be required B. Less chlorine concentration would be required C. More contact time would be required D. Water temperature does not affect the effectiveness of chlorine - ANSWER-C. More contact time would be required If a confined space has 20.9 % oxygen content , what does this tell you ? A. Oxygen content is too high to enter B. Oxygen content is too low to enter C. Confined space is safe to enter D. The oxygen content must always be 10%. Therefore, it is not safe to enter. - ANSWER-C. Confined space is safe to enter What could be the problem if an excessive amount of water is leaking from the stuffing box ? A. Packings may need to be replaced, or the packing gland may need to be tightened. B. Check valve may need maintenance C. Impeller is cracked D. Cavitation - ANSWER-A. Packings may need to be replaced , or the packing gland may need to be tightened .