Water Softners

Where water is very hard, the local utility company often brings mineral content to within a moderate range of 5 or 6 grains per gallon (GPG). But this is still fairly hard because a utility company’s water is used for many purposes where softening is unnecessary or irrelevant, such as for watering public parks.

http://www.hometips.com/repair-fix/solving-hard-water-problems.html