A water ozonization system equipped with a filter in that water can be treated with ozone through the steps of installing a diverging pipe therein to allow part of raw water to diverge from the discharge side of a raw water pump, the diverging pipe being fitted with an ejector; injecting and introducing the ozone obtained from an ozonizer into the ejector via its suction port in order to form ozonous water; returning the ozonized water via a diverging pipe to the suction side of the raw water pump; and supplying the ozonous water and unreacted ozonizing gas to the whole quantity of raw water within the limit to which the raw water pump produces no cavitation so as to increase ozone absorption efficiency with the agitation of pump impellers for accelerating ozonization and the reaction of the unreacted ozonizing gas in the raw water pump on the whole quantity of the raw water by ozonizing means.
