FloJet - RV Macerator Pump - 18550000A. Designed to add flexibility to Holding Tank service. With the Flojet Waste Pump you can not only empty the black and grey water tanks at the conventional Dump Station, but also down a toilet, into your house sewer clean-out, septic tank or into a mobile waste wagon.. The Flojet macerator pump will empty a typical 30-gallon holding tank in less than three minutes. The time increases somewhat as the distance pumped is increased beyond 25'. The pump will mace