Water softener salt helps remove minerals from your hard water, including iron, calcium, magnesium, and even barium. These hard water minerals are removed when water passes through resin beads in the water softener tank. Salt or potassium chloride is used to periodically recharge the resin beads so that they can continue to remove these minerals.

Water softening is used in commercial and residential applications where these problems are avoided.  It is designed to remove specific anions (positively charged ions) from the water.