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Water Distribution & Storage Systems Flashcards

7 cards from real WTO practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Water Distribution & Storage Systems flashcards as text

  1. What is the primary purpose of a pressure-reducing valve (PRV) in a water distribution system?

    Answer: Reduce high upstream pressure to a safe downstream level

    A PRV automatically reduces high upstream pressure to a lower, controlled downstream pressure to protect pipes and meters.

  2. Which type of water storage tank is typically used to equalize pressure in a distribution system while providing fire flow reserve?

    Answer: Elevated storage tank

    Elevated storage tanks use gravity to maintain system pressure and provide reserve volume for peak demand and fire protection.

  3. A distribution main showing a consistently low chlorine residual at the end of the line most likely indicates:

    Answer: Excessive detention time causing chlorine decay

    Long detention times in dead-end or low-flow mains allow chlorine to dissipate, resulting in low or zero residuals at the extremities.

  4. The Hazen-Williams formula is used in water distribution to calculate:

    Answer: Head loss due to friction in a pipeline

    The Hazen-Williams formula relates flow rate, pipe diameter, pipe roughness coefficient, and hydraulic gradient to estimate friction head loss.

  5. Cross-connection control programs are primarily designed to protect against:

    Answer: Backflow of contaminated water into the potable supply

    Cross-connection control prevents non-potable substances from entering the drinking water system through unprotected connections.

  6. When flushing a water main to restore chlorine residual, the operator should flush at a velocity of at least:

    Answer: 2.5 ft/s

    AWWA recommends a minimum flushing velocity of 2.5 ft/s (0.76 m/s) to effectively scour sediment and biofilm from pipe walls.

  7. In a looped distribution system, what is the main advantage over a dead-end (branching) system?

    Answer: Water can reach any point from two directions, improving flow and reliability

    Looped systems allow flow from multiple directions, reducing pressure loss and ensuring supply continuity if one segment is taken out of service.