Put quite simply, hard water has more minerals in it than soft water. Rainwater is naturally soft – it contains only small amounts of minerals. But as the water passes through rocks, such as chalk and limestone, minerals in the rocks are dissolved in the water, giving it its hard nature. Calcium carbonate is the mineral most commonly associated with water hardness. This is the same mineral found in many calcium supplements sold by your local drug or health food store. Hard water reduces the “sudsing” ability of soap and may cause spots on your dishes and glasses after washing and air-drying. Soft water is water that is low in calcium carbonate.
Calcium carbonate is an essential nutrient that is used by your body to fortify bones and teeth. It also helps your muscles to function properly. Water hardness is measured in milligrams per Liter or grains per gallon. The hardness of the SUB’s tap water is typically around 20 to 100 milligrams per Liter or 1 to 6 grains per gallon.