A structure improvement for a water purifier includes a streamlined main body combined by a pair of the symmetrically arranged half housings each of which has a large opening closed by a lid, a motor unit, a pipeline and a flat rectangular rack disposed inside the main body, a plurality of the membrane pipes and the filter element horizontally and superimposedly secured to two sides of the rack automatically connected to the pipeline and a water outlet. A bottom and a cup seat at front side, a socket aside several pipes and plurality of the air vents at rear side of the main body, an arcuate handle on the top, a sensor, an electric circuit card and a TDS (total dissolved solids) remover device inside the main body.