My parents drink tap water, but every morning my father would pour away a few liters of water in case the supply pipe was made of lead and the water sitting in

My parents drink tap water, but every morning my father would pour away a few liters of water in case the supply pipe was made of lead and the water sitting in it overnight had absorbed some. (This is actually the official government advice in the UK, if your house is older than 1970. Of course, the better option is to replace it with non lead, if you can.)