I live in London and use cold tap water to boil to prepare the formula for my baby.("Breast is best people - please don't start - do you think we don't do it for fun?) The problem is that there is a white deposit that is formed on the water surface just after it is boiled - is it the same stuff as scaling in other gadgets and if so isn't it harmful to the baby? How is it possible to get rid of this? Or is it better to use bottled still water?