To provide a raw water feeding apparatus in which a clogging can always and surely resolved even when the clogging is caused at any part of a loop section of a raw water feeding pipe.

In the raw water feeding apparatus, the loop section 1a of the raw water feeding pipe 1 constituted by forming the loop section 1a at its top end is arranged in a treating tank 10 and raw water is fed into the treating tank 10 from two or more jetting ports formed at the loop section 1a. Further a part of the loop section 1a of the raw water feeding pipe 1 is provided spreadingly out of the treating tank 10, an electrically operated valve (a first valve) V1 is provided at a part outside the treating tank 10, further an end part of a return pipe 2 branching from a part outside the treating tank 10 is opened in the treating tank 10 and an electrically operated valve (a second valve) V2 is provided at the return pipe 2. When washing, the electrically operated valve V1 is closed and the electrically operated valve V2 is opened.