When should a rapid sand filter be backwashed?

Backwashing a rapid sand filter is necessary to maintain its effective operation and ensure the proper removal of impurities from the water. The correct timing for backwashing is based on the differential pressure, or head loss, across the filter media.

When the loss of head gauge indicates between 6 and 10 feet, it signals that the filter media is becoming clogged with particulate matter. This build-up of debris restricts water flow and reduces the filter's efficiency. Backwashing at this point helps to dislodge accumulated particles, allowing clean water to flow through the filter again, restoring its function.

Performing backwashing too infrequently could lead to decreased water quality, while doing so too often may waste water and resources. Therefore, the specified range of 6 to 10 feet on the loss of head gauge is an established practice in managing the maintenance of rapid sand filters effectively.