In a precipitation softener, you will get a double replacement reaction. The calcium carbonate will be precipitated, and since the calcium salts are responsible for the hardness it will soften the water. The introduction of sodium into the water can be perilous for people who have high blood pressure, while people that have low-sodium intakes cannot use water preserved by these softeners. Other forms of softener are mostly ion-exchange based, though purification and reverse osmosis are possible selections. These tend to be affluent for collective use, as distillation entails a lot of heat, and reverse osmosis involves pumps and distinct membranes, which have to be changed frequently.
