Usually when you want to change the salt in your water softener you can choose from either sodium chloride crystals pellets and block salt or potassium chloride the type of salt you use can affect the efficiency of your water softener and the regeneration process. If you have a salt based water softener you can use evaporated salt solar salt rock salt and sometimes block salt for your system it also goes without saying that youll only need salt if your water softener is salt based. Type of salt to use for macclean water softener golden education world book document id b47a6157 golden education world book for water softeners should be used do not . Finally rock salt and block salt are sometimes used as a water softener salt however neither of these is recommended because the former has a high content of calcium sulfate and therefore doesnt always dissolve well in water and the latter because it is difficult to dissolve in most systems