Today's question: What is "hard" water?
"Plain Talk" answer: Hardness in drinking water is caused by calcium and magnesium - two nontoxic, naturally occurring minerals in water. If calcium or magnesium is present in your water in substantial amounts, the water is said to be hard because lathering soap for washing is difficult to do, and cleaning with hard water is inefficient. Water containing little calcium or magnesium is called soft water and is better for laundering and other purposes.
Other indications of water that is excessively hard include clothes that look dingy and feel harsh and scratchy after laundering; spots on dishes and glasses after they've been washed; filmy showers doors; and sticky, dull hair, even after washing. A buildup of mineral deposits can also reduce water flow in domestic pipes, and faucet aerators may become plugged if not cleaned often.
For more information on this and many other water-related topics, check out "Plain Talk About Drinking Water" by Dr. James M. Symons.