A water treating method includes a step of installing a cavitation generation ring in a part of a water communication pipe, and a step of passing water through the inside of the cylindrical portion at high pressure, thereby cavitation being generated in the cylindrical portion and clusters of molecules of water being fined. A cavitation generation ring is configured to be installed in a part of a water communication pipe. A water treating apparatus includes a cavitation generation ring, a water communication pipe and a pressurizing pump for water.
