What is hard water?
Rain water is water in its purest form. As it filters through the earth, it absorbs minerals such as calcium and magnesium. These minerals make water hard. How hard the water becomes depends on how much of these minerals it dissolves. Different degrees of hardness exist depending on the amount of minerals dissolved in the water. Water hardness can vary greatly based on where you live.
Soft water is defined as 0 to 1 grains per gallon. Slightly hard water is 1 to 3 1/2 grains per gallon. Moderately hard water has 3 1/2 to 7 grains of minerals per gallon. What is defined as hard water has 7 to 10 1/2 grains per gallon. Finally, the hardest water has over 10 1/2 grains of minerals per gallon.