A filter must be whitewashed when a head loss of 6 to 10 feet occurs.

A filter must be whitewashed when a head loss of 6 to 10 feet occurs.

• A. True
• B. False
• C. Only during backwash
• D. Only when head loss exceeds 15 feet

Answer: (B)

Whitewashing a filter bed is a maintenance step used to protect the surface and control algae growth, not a reaction to a specific head loss reading. Head loss is tracked to decide when to backwash the filter, which removes accumulated material and restores flow. Whitewashing is typically done during construction or after major maintenance that disturbs the bed, or at planned maintenance intervals, rather than at a particular head loss value. So tying whitewashing to a 6–10 feet head loss isn’t how it’s used in routine operation.

Whitewashing a filter bed is a maintenance step used to protect the surface and control algae growth, not a reaction to a specific head loss reading. Head loss is tracked to decide when to backwash the filter, which removes accumulated material and restores flow. Whitewashing is typically done during construction or after major maintenance that disturbs the bed, or at planned maintenance intervals, rather than at a particular head loss value. So tying whitewashing to a 6–10 feet head loss isn’t how it’s used in routine operation.