Abstract: A portable, manually-operated water filtration pump for purifying water. The pump includes an inexpensive, disposable filter cartridge which can be easily changed when the filter elements are no longer effective. The pump uses a lever to actuate a double-acting piston. The lever is collapsible to one side of the pump for compact storage. The filter cartridge is a tubular cylinder having an inner bore forming the pump cylinder. A cylindrical mechanical filter is concentric with and adjacent to the inner bore to filter out particulates larger than 0.3 microns. A fluidized granular activated charcoal filter surrounds the mechanical filter to absorb chlorine and chlorine-related compounds such as herbicides and pesticides. The pump pumps filtered water into a bottle adaptor which will fit most standard water containers. A prefilter is provided to screen out large particulates from the pump to enhance the life of the filter elements.