Water-Softening Plant Design

In Ohio, the water supplies available in sufficient quantities to justify their development for municipalities are hard, almost without exception. The ground-waters used for municipal supplies range from about 60 ppm at a few supplies, derived from the sandstone region in the south eastern part of the State, to about 2 000 ppm in the north western part. The hardness of the surface water supplies does not vary through such a wide range. The average hardness of the Ohio River water throughout the year is about 100 ppm and the average hardness of the Lake Erie water is about 115 ppm. Most of the surface waters from streams within the State have an average hardness between 100 and 400 ppm; the maximum and minimum hardness of these surface waters fluctuates considerably above and below these averages.

Thus, it is seen that Ohio has been, and still is, a natural field for water softening. The first water-softening plant in the United States was installed in 1903 at Oberlin, and the first large plant in the United States was placed in operation at Columbus, in 1908. Very few plants were installed during the next fifteen years, there being a total of only six municipal water-softening plants installed in Ohio prior to 1924. Since 1924 the number of municipal water-softening plants has increased rapidly and, when plants now (April 1, 1938) under construction are completed, there will be 93 plants in the State. A total of approximately 4 800 000 population is supplied by the 450 municipal water-works systems in Ohio and 1 450 000 of these persons are supplied with softened water.