PURPOSE: To remove chlorine odor from city water and to restrain the generation of rust, corrosion and scale in water piping, and fur, scale, etc., in a discharge port, and bacteria by introducing treated water into a vessel, giving prescribed ceramic particles fluidization, mutual friction and collision by water flow to activate the treated water and taking out the formed activated water.

CONSTITUTION: Ceramic particles 1 consisting of a spherical sintered body of oxide base ore powder whose main components are silicon and aluminum and which contains an alkaline metal and/or an alkaline earth metal are fed into, for example, a cylindrical vessel 2 made of stainless steel. And treated water is introduced from an introducing port 3 in the lower part of the vessel 2. By the water flow of the treated water, ceramic particles 1 are given fluidization, mutual friction and collision in water, causing the treated water to be activated. The formed activated water is taken out from an activated water discharge port in the upper part of the vessel 2. Besides, in the upper and lower parts of the vessel 2 are installed mesh-shaped partition plates 5, 6 through which water is passed but ceramic particles 1 are not passed.