We have developed a new, continuous water-purification system that uses high-T_c bulk superconductors to rapidly remove contaminants from water supplies, The maximum magnetic field of the magnetized bulk superconductors is 3.2 T. This membrane-magnetic separator consists of (1) a preapplication treatment unit in which magnetic flocs made up of suspended solids and seeded with ferromagnetic particles are coagulated in a flocculation vessel, (2) a membrane separator that purifies water using a rotating net to gather the flocs and (3) a magnetic separator that recovers the magnetic flocs from the net. This system simultaneously removed 98% of the contaminants from sewage at our factory and recovered sludge at a concentration of 40, 000mg/L. Moreover, it removed 90% of the oil from oily water and recovered sludge at a concentration of 23, 000mg/L. Treatment time was only four to five minutes, and we found that the new system is capable of treatment and sludge recovery at higher speeds than conventional flocculant deposition methods.