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One of the subjects that comes up a lot around here is Hard Water. The most common question is: How do I know if my water is hard or soft?

The answer is: Unless you live in Boston, Seattle, Hawaii, or Alabama, you most likely have hard water. See, in the good ‘ol USA, water hardness is measured in Grains per Gallon (gpg) as defined as 1 grain (64.8 mg) of calcium carbonate per U.S. gallon (3.79 liters) of water, or 17.118 ppm. Check with your local water provider to find out if you have hard water in your region. They usually do an annual report and you can get a copy of it, if you didn’t already get one in the mail.

Characteristics of Hard Water

Hard water resists foaming, so usually cleaning compound manufacturers add heaps of a foaming agent called Sodium Laureth Sulfate. It makes a lot of bubbles, but be forewarned: it combines with the calcium to create deposits that stains anything it touches: windows, tiles, spas, showers, etc. These deposits, called “scale,” are composed mainly of calcium carbonate, magnesium hydroxide, and calcium sulfate. The problem gets even worse when you add detergents (aka surfactants), as the positive calcium ions (present in hard water) mix with the detergent to create a film of soap scum instead of lather. Now add the residue from the sodium laureth sulfate and it makes a kind of ‘cement’ that’s really hard to remove.

Water Hardness or Softness in the USA

These deposits, called “scale,” are composed mainly of calcium carbonate, magnesium hydroxide, and calcium sulfate.

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