Abstract: A portable liquid-filtration device includes an inlet port, a filtering portion including a filtering medium and fluidly coupled to the inlet port, a filtered-liquid output port fluidly coupled to the filtering portion, a flush port fluidly coupled to the filtering portion, and a manually activated pump assembly fluidly coupled to the inlet port, filtering portion, output port and flush port. The pump assembly is configured, when activated, to create a negative fluid pressure at the inlet port and a positive fluid pressure at the output port and the flush port. As a consequence of activation of the pump assembly, the filtering portion receives unfiltered liquid from the inlet port, the output port receives from the filtering portion only liquid traversing the filtering medium in a first direction, and the flush port receives from the filtering portion liquid traversing the filtering medium in a second direction different from the first direction.