CWS Installation, Maintenance & Troubleshooting 3 — Questions and Answers
Question 1: When sizing a water softener for a household, which factor is NOT required for the calculation?
- Number of people in the household
- Daily water usage per person
- Source water hardness in grains per gallon
- The color of the inlet plumbing (Correct answer)
Correct answer: The color of the inlet plumbing
Softener sizing requires daily flow demand and hardness level to calculate daily grain removal need; plumbing color has no bearing on capacity calculations.
Question 2: A technician notices that a water softener is drawing brine but not rinsing properly, leaving salty water at the tap. What is the most likely component to inspect first?
- The brine injector (venturi) and screen (Correct answer)
- The resin tank o-ring
- The distributor tube
- The salt grid in the brine tank
Correct answer: The brine injector (venturi) and screen
A fouled injector or clogged screen restricts the rinse water flow, preventing complete removal of brine from the resin bed.
Question 3: What is the recommended practice when connecting a water treatment device to copper plumbing using a dielectric union?
- Apply Teflon tape only to the copper threads
- Install the dielectric union to prevent galvanic corrosion between dissimilar metals (Correct answer)
- Solder the union directly to the device port
- Use a brass-to-copper direct connection without insulation
Correct answer: Install the dielectric union to prevent galvanic corrosion between dissimilar metals
Dielectric unions contain an insulating liner that separates dissimilar metals, preventing galvanic corrosion that would otherwise degrade the connection over time.
Question 4: An iron filter using air injection shows rust-colored water at the tap after regeneration. What adjustment is most appropriate?
- Increase the backwash rate
- Decrease salt dosage
- Extend the backwash duration (Correct answer)
- Reduce the air injection volume
Correct answer: Extend the backwash duration
Extending the backwash duration allows more time to flush oxidized iron particles from the media bed, preventing carryover into the service line.
Question 5: Which of the following is the correct sequence for sanitizing a newly installed reverse osmosis system before placing it into service?
- Flush with hot water, add bleach, then flush again with cold water
- Add NSF-approved sanitizer, let soak, flush thoroughly until no sanitizer is detected (Correct answer)
- Run three full tank cycles without sanitizing to flush manufacturing residues
- Pressurize the system and test for leaks before any sanitizing step
Correct answer: Add NSF-approved sanitizer, let soak, flush thoroughly until no sanitizer is detected
NSF-approved sanitizer is introduced, allowed to contact all surfaces for the recommended contact time, then thoroughly flushed until no residual sanitizer remains.
Question 6: A customer's carbon filter is producing musty-smelling water shortly after installation. What is the most likely cause?
- The carbon media was not properly backwashed and fines remain (Correct answer)
- The incoming water pH is too high
- The system pressure is too low
- The filter housing was installed upside down
Correct answer: The carbon media was not properly backwashed and fines remain
New carbon media contains carbon fines and dust that can harbor bacteria or cause taste/odor issues if not properly backwashed and flushed prior to service.
Question 7: What does a continuously running drain line on a water softener during the service (non-regeneration) cycle typically indicate?
- High water pressure in the supply line
- A stuck or worn control valve seal allowing water to bypass to drain (Correct answer)
- Normal operation of the overflow protection
- The system is in the rinse phase
Correct answer: A stuck or worn control valve seal allowing water to bypass to drain
Water flowing to drain outside of regeneration usually means a worn or damaged seal in the control valve is failing to close off the drain port during the service cycle.
CWS Installation, Maintenance & Troubleshooting 3
When sizing a water softener for a household, which factor is NOT required for the calculation?