METHOD FOR CONTROLLING PH BY ELECTRICAL CONDUCTIVITY

Provided is a method for controlling pH to a neutral region (pH 6-8) by adding an alkali or acid to decarbonated water, wherein the addition amount of the alkali or acid is controlled by using an electrical conductivity meter. The decarbonated water is obtained by decarbonating industrial water or underground water to have a carbonate concentration of 10 ppm or less. The method may further comprise a step for RO-treating the decarbonated water, which has been adjusted to pH 6-8 by the pH control, to produce pure water. 一种pH控制方法，在将碱或酸添加于脱碳酸处理水而将pH控制为中性范围(pH6～8)的方法中，利用电导率计来控制碱或酸的添加量。脱碳酸处理水是将工业用水或地下水以使碳酸浓度成为10ppm以下的方式进行了脱碳酸处理的水等。所述pH控制方法还具有：对通过所述pH控制而调节为pH6～8的脱碳酸水进行RO处理来制造纯水的工序。