What happens to a filter bed during backwashing if excessive pressure is applied?

When excessive pressure is applied during the backwashing of a filter bed, it can lead to cracking within the filter media. This cracking can compromise the structural integrity of the filter bed, causing media loss as particles break apart or are dislodged. The backwashing process is intended to clean the filter by reversing the flow of water to dislodge trapped contaminants. However, if the pressure is too high, rather than effectively cleaning the bed, it might instead damage the media, making it less effective in future filtration operations. This situation can lead to increased operational costs and a decrease in water quality due to the potential release of broken media back into the system.

The other options do not accurately reflect the consequences of applying excessive pressure during backwashing. While the filter bed may become less effective or appear to expand under certain conditions, these scenarios are not the primary concern when excessive pressure is involved, as cracking and media loss are the more immediate and significant risks.