Question: What is hard water?

Answer: Hardness in drinking water is caused by two nontoxic chemicals (usually called minerals) calcium and magnesium. If calcium and/or magnesium is present in your water in substantial amounts, the water is said to be hard because making a lather or suds for washing is hard (difficult) to do. Thus, cleaning with hard water is hard / difficult. Water containing little calcium or magnesium is called soft water. (Maybe it should be called easy, the opposite of difficult.)