However, the salt blocks used for animal nutrition generally contain binders or additives incompatible with water softener units. Use block salt only in those units specifically designed for this form of salt. Make certain you use those made from high-grade evaporated salt without binders or additives. Rock salt is a natural product that may have high levels of soluble or insoluble impurities. If the soluble impurities are salts of calcium or magnesium, they can significantly reduce the effectiveness of the chemical regeneration process.
Insoluble impurities can collect in the brine tank or softener bed.
This increases pressure drop, plugs valves, and requires more maintenance than usual. When using rock salt, always select those averaging less than one percent impurities. Additives may be included with the salt to keep the softener bed from being clogged with iron. Selecting this specially formulated salt may be desirable when the water supply is high in iron. If softened water is used for cooking and drinking, the added sodium could be troublesome for individuals on sodium-restricted diets due to health problems such as hypertension.