Why can grit damage wastewater treatment equipment?

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Aerial view of wastewater treatment basins with circular clarifiers; overlaid toilet graphic and arrow with text reading: “Where does it go?” — wastewater treatment All the sewers in your neighborhood end up here.

In the context of wastewater treatment, grit—which includes materials like sand, coffee grounds, and eggshells—must be removed because it causes excessive wear and tear on pumps and other mechanical plant equipment.1

Because grit is abrasive, its presence in the flow can damage machinery as it moves through the system. This is especially critical in cities with combined sewer systems, where significant amounts of silt, sand, and gravel are washed into the wastewater stream during storm events. To protect downstream infrastructure, grit chambers are used to slow the flow of water, allowing these heavy solids to settle out before they can reach and harm sensitive equipment.1