Central water purification device capable of realizing quality-divided reflux preservation

The utility model discloses a central water purification device capable of realizing quality-divided backflow preservation. Comprising a water inlet, a water inlet electromagnetic valve, a raw water bucket, a first booster pump, a coarse filtration system, a precision filter, a second booster pump, a reverse osmosis membrane filtration system, a pH adjusting system, a water purification bucket, a water supply ultraviolet sterilizer, a water supply pump set, a water supply system, a TDS detector, a first backflow electromagnetic valve, a second backflow electromagnetic valve, a rear activated carbon filter and a backflow fresh-keeping system. And a central control system. According to the utility model, an on-line quality-divided backflow fresh-keeping link is added aiming at the return water of a water supply system pipeline of the original central water purification equipment, the central control system controls the opening and closing of the backflow electromagnetic valve according to the result of the TDS