I'm lucky that the area I live in has good water and I can use water direct from the tap if I choose. I do prefer, however, to use water that has sat overnight or been boiled first to get the chlorine out. If you do have hard water or anything that stains or leaves spots, you are best off with distilled water. It's cheap enough that when you compare the cost of a good iron to a year's worth of water -- get the water! Water softeners often work with salt so that can leave a crust/spot. It's not that bad a thing to get, you just put it on the grocery list.