top of page

Water Hardness

Updated: Oct 14, 2023

The Water We Use

When I travel I seldom give much thought to the water I drink, cook with, and bathe in. But there are occasions when something seems a little "off" with the water. Sometimes it's the taste, a hint of hydrogen sulfide, which makes for a very bad cup of coffee, or perhaps the water just seems to be too metallic in taste. More often though a problem with the water reveals itself in one of two ways:

1) I can't generate any soap suds in the shower, or

2) The opposite happens and I can't seem to rinse the plentiful soap suds off leaving my skin feeling a little slippery, soapy, and unclean.

What I can never keep straight are the simple reasons for each of these two scenarios. So I'm going to write about it here.

Woman drinking glass of water.

Hard water is found in 85% of the United States and is generally preferred for drinking due to its better taste. But hard water makes it difficult to generate soap suds because the soap interacts with calcium, magnesium, and other minerals in the water. This interaction prevents the soap from performing an effective clean when it comes to dirty clothes or dishes. Hard water leaves a residue behind creating a soap film in baths and showers and scale in piping and water heaters.

Soft water on the other hand, having replaced the calcium and magnesium ions with salt (or potassium), which might make the water taste a little salty, leaves your skin feeling slippery as you rinse the soap off. Surprisingly, that slippery feeling is an indication your skin is clean! Soft water doesn't have mineral interference, resulting in the need for less soap in addition to achieving cleaner clothes, dishes, and skin.

The following information is from the USGS website (

Many industrial and domestic water users are concerned about the hardness of their water. Hard water requires more soap and synthetic detergents for home laundry and washing, and contributes to scaling in boilers and industrial equipment. Hardness is caused by compounds of calcium and magnesium, and by a variety of other metals. General guidelines for classification of waters are: 0 to 60 mg/L (milligrams per liter) as calcium carbonate is classified as soft; 61 to 120 mg/L as moderately hard; 121 to 180 mg/L as hard; and more than 180 mg/L as very hard.

Patterns of hardness in the United States are shown on the map of accounting units below. Softest waters were in parts of New England, the South Atlantic-Gulf States, the Pacific Northwest, and Hawaii. Moderately hard waters were common in many rivers of Alaska and Tennessee, in the Great Lakes region, and the Pacific Northwest. Moderately hard waters were common in many rivers of Alaska and Tennessee, the Great Lakes region, and the Pacific Northwest. Hard and very hard waters were found in some streams in most of the regions throughout the country. Hardest waters (greater than 1,000 mg/L) were measured in streams in Texas, New Mexico, Kansas, Arizona, and southern California.

USGS Hardness Map of United States


Search by Tags
bottom of page