PURE WATER MANUFACTURING METHOD

PROBLEM TO BE SOLVED: To provide a pure water manufacturing method wherein no scale is generated in a reverse osmosis membrane, an addition amount of alkali required for pH control is reduced, pure water of improved quality can be obtained, and stable operation is possible. SOLUTION: In the method, the pure water is manufactured by controlling raw water at pH 9 or higher and making the water to pass through a reverse osmosis membrane device. The method is provided with a process adding a scale inhibitor containing a polymer having a carboxyl group in a side chain as an active ingredient before making the water pass through the reverse osmosis membrane device, and making the water to pass through the device. COPYRIGHT: (C)2005,JPO&NCIPI