Over time, your steam iron will start to build up calc or scale; this happens in all electrical appliances that use water. The harder the water in your area, the faster scale impurities will develop and solidify if not cleaned away. Without regular descaling, you will find that scale is pushed out of your steam iron in the form of white/brown stains and that the steam output is compromised. Be sure to descale as part of your ironing routine to maximize the performance of your steam iron.