Major-ion chemistry in groundwater is relatively stable and generally does not change over time. Water hardness is based on major-ion chemistry concentrations. Colors represent streamflow from the hydrologic-unit area. Mean hardness as calcium carbonate at NASQAN water-monitoring sites during the 1975 water year. Just as in the human body where blood vessels can be reduced in inside diameter due to cholesterol buildup, water pipes can gradually close up resulting in less water movement through the pipe and a lowering of water pressure. Hard water can even shorten the life of fabrics and clothes (does this mean that high-school students who live in areas with hard water keep up with the latest fashions since their clothes wear out faster?).Īs the image of the inside of a water-supply pipe shows, long-term movement of hard water through a pipe can result in what is called scale buildup. In areas of the country where the water is relatively hard (see map below), industries might have to spend money to soften their water, as hard water can damage equipment.

Water hardness varies throughout the United States. Water is a great solvent for calcium and magnesium, so if the minerals are present in the soil around a water-supply well, hard water may be delivered to homes. Water systems using groundwater as a source are concerned with water hardness, since as water moves through soil and rock it dissolves small amounts of naturally-occurring minerals and carries them into the groundwater supply. 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. Hardness is caused by compounds of calcium and magnesium, and by a variety of other metals. Humans need minerals to stay healthy, and the World Health Organization (WHO) states that drinking-water may be a contributor of calcium and magnesium in the diet and could be important for those who are marginal for calcium and magnesium intake. These newly charged particles become attracted to the positive and negative charges in water and can be washed away easily.īut hard water can have some benefits, too. And, yes, mineral buildup will occur in your home coffee maker too, which is why some people occasionally run vinegar (an acid) through the pot. The acidity of vinegar helps to dissolve mineral particles by making them charged. This scale can reduce the life of equipment, raise the costs of heating the water, lower the efficiency of electric water heaters, and clog pipes. When hard water is heated, such as in a home water heater, solid deposits of calcium carbonate can form. Many industrial and domestic water users are concerned about the hardness of their water. Have you done a load of dishes in the dishwasher, taken out the glasses, and noticed spots or film on them? This is more hard-water residue-not dangerous, but unsightly. One of the most common causes of cloudy dishes and glassware is hard water.

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Scum map water locations