Calgon 4-in-1 water softener gel is fast acting to boost efficiency for your washing machine by removing limescale and helping your washing machine to live longer. It's suitable to use alongside your washing liquid, washing capsules and washing powder. Simply add one dose of Calgon 4in1 gel to each wash into the detergent section of your washing machine with your laundry in addition to your usual laundry detergent for limescale prevention, rust prevention, removal of dirt and residue as well as odour elimination.