I make sure it is cool, unplug it, take the container bits off the base, pour our any leftover water, then pour in enough white vinegar to cover the element. I leave it for a while, maybe half an hour to an hour, depending on how scaled it is (mine is never bad as I do it regularly) then pour the vinegar away. I might rub gently with a piece of muslin if there are any bits that are loose/gritty. Then rinse a few times with fresh water.