Practice Test Geeks(CWS) Certified Water Specialist Practice Test
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Point-of-Use vs Point-of-Entry Systems Flashcards

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

Read the first 7 Point-of-Use vs Point-of-Entry Systems flashcards as text

  1. Which NSF/ANSI standard applies to POU drinking water systems that use activated carbon for taste-and-odor reduction?

    Answer: NSF/ANSI 42

    NSF/ANSI 42 covers aesthetic effects (taste, odor, chlorine) for both POU and POE drinking water treatment systems.

  2. A family on a municipal supply complains of dry skin and scale on fixtures throughout the home. The MOST appropriate treatment is:

    Answer: POE ion-exchange water softener on the main line

    Hardness affecting the entire home—skin, fixtures, and appliances—is best corrected with a POE softener that treats all water entering the residence.

  3. In a POE ion-exchange softener, hardness ions (Ca²⁺ and Mg²⁺) are exchanged for:

    Answer: Potassium or sodium ions from the resin

    During the service cycle, hardness ions are exchanged for sodium (or potassium if potassium chloride salt is used) held on the cation exchange resin.

  4. A POU pitcher filter certified to NSF/ANSI 53 can be used to reduce which contaminant category?

    Answer: Health-effects contaminants such as lead and cysts

    NSF/ANSI 53 covers health-effects reductions (e.g., lead, cysts, VOCs) for both POU and POE drinking water treatment devices.

  5. A well owner installs a POE chlorination system with a contact tank. What is the primary purpose of the contact tank?

    Answer: To provide sufficient contact time for chlorine to disinfect the water

    The contact tank holds chlorinated water for a calculated detention time (CT) so the disinfectant has adequate time to inactivate pathogens.

  6. When a POU system is installed on a rental property, which practical advantage does it offer over a POE system?

    Answer: It can be removed and reinstalled at a new location with minimal modification

    POU units are typically compact and portable, allowing tenants or service companies to remove and reinstall them when moving without major plumbing modifications.

  7. A POE system that uses ozone injection for disinfection must typically be followed by:

    Answer: A carbon filter to remove excess ozone before water reaches fixtures

    Residual ozone degrades to oxygen and can produce bromate in waters with bromide; a downstream carbon filter quenches excess ozone and adsorbs byproducts before distribution.