Abstract: Method and apparatus for the control of deposition of contaminants in pumping systems. The method includes the steps of periodically stopping the pump and back feeding chlorinated water and/or surfactants and other organic or inorganic acids at a reduced flow rate through the outlet pipe of the pump and through the pump itself to control the deposition of materials by bacterial action and/or to control biofouling and/or abiotic encrustation. The apparatus includes a bypass and valving to provide a back flow of the chlorinated water and/or surfactants and other organic or inorganic acids through the pumping installation at a relatively slow flow rate and equipment for the feeding desired decontaminants into the back flow.