Question:
A friend has a water softener that he dumps in a bag of special salt into a few times a year. The water doesn't seem to wash across the salt as I can touch the salt and the water line is a closed pressurized system. How the heck does this work? I'm baffled

Answer: In short hard water is hard because it has hard stuff in it like calcium. A water softener has stuff called resin in one tank. The water flows over the resin and the calcium is held there and sodium is put in it's place. That is called an ion exchanger.

The salt (sodium chloride) is the source of the sodium and the salt water is flushed through the resin from time to time to refresh the supply of sodium. The waste produce is calcium chloride.

Take a look at: http://www.howstuffworks.com/question99.htm For a better and longer explanation.

I loved the time a salesman came to the house and tried to sell me a unit. Each time I asked a question he could not answer it, or answered it dead wrong. He had no idea how one worked and could only repeat the canned spiel.

I had time to kill so I kept interrupting with simple questions like "What does the salt do?" and each time he had to start over. Eventually he gave up. It was fun while it lasted.

Hardness is a measurement of the ability of water to precipitate soap, and mostly comes from calcium and magnesium.

In fresh water systems calcium carbonate and calcium bicarbonate are usually the dominant dissolved minerals and if in high concentrations are thus both hard and alkaline. However natural water can also contain significant amounts of magnesium sulfate which contributes to hardness but not alkalinity (can be hard and acid), sodium carbonate which contributes to alkalinity but not hardness (soft with high pH), and sodium chloride which contributes to neither (soft with low alkalinity).

Four ways to soften water are; Ionic Exchange, Deionization, Distillation and Reverse Osmosis.