PURPOSE: To provide a forcibly feeding system for water to be treated which is labor-saving and simplified and excels in economy and in which a booster pump station is made unmanned and further various kinds of the purification treatment of water to be treated are assembled in the same location for forcibly feeding water to be treated, such as untreated domestic waste water and industrial waste water, to a waste water treating plant.

CONSTITUTION: In a forcibly feeding system for water to be treated having a booster pump station for forcibly feeding water to be treated to a treatment facility through a forcibly feeding pipe 2, the booster pump station has at least an inflow port in which untreated waste water flows, a sand basin 8, a pump well 6 and a forcibly feeding pump 1 and the forcibly feeding pipe 2, and at least one of a residue separated by a screen 12 at the inflow port, sand precipitated in the sand basin and scum 4 floating on the surface of the water in the pump well 6 is forcibly injected into the discharge side and/or suction port side of the forcibly feeding pipe and forcibly fed to the treatment facility together with the water to be treated by the forcibly feeding pump 1 installed in the pump well.