When should a filter be backwashed?

A filter should be backwashed when head loss across the filter reaches a predetermined limit because this indicates that the filter media is becoming clogged with particulates and debris. As water flows through the filter, particles are trapped, leading to an increase in resistance to flow, which is measured as head loss. When head loss reaches a specific threshold, backwashing is necessary to reverse the flow and dislodge the accumulated materials, effectively cleaning the filter and restoring optimal flow rates.

This process not only helps maintain the filter's efficiency but also ensures that the water quality remains high, as clogged filters can lead to reduced filtration performance and potential contamination of the treated water. Regular monitoring and backwashing based on head loss help maintain the longevity and effectiveness of the filtration system.