A water softener may stop working properly for a number of reasons. The very first thing you need to check is if the brine solution is mixing properly as you may need to add salt to the tank. Other issues that may arise with decreased efficiency of a water softener may require a part replacement. A water softener's purpose is to remove excess minerals and calcium from certain water sources because they can destroy your household fixtures and leave calcium stains on tubs. If the brine solution is not the culprit, then check the following common parts that may need adjusting or replacing.