Catchpit

A catchpit is a chamber with an internal sump that intercepts and retains silt, grit, leaves and other debris from surface water before flows continue into the main drainage system. They are commonly installed on highway drainage, car park run-off and at the inlet to soakaways and attenuation tanks. The trapped material settles to the base of the sump while cleaner water passes over an outlet weir or pipe. UK Building Regulations Part H3 and SuDS guidance generally require catchpits or similar pre-treatment where surface water discharges to ground or watercourse. Catchpits need regular emptying using a vacuum tanker, particularly after autumn leaf fall and following major storms. Without scheduled maintenance, silt build-up reduces capacity and can lead to blockages further down the drain run.