When I was a kid, one of the things I never understood was why we had to fill the pasta pot with cold water. If I filled it with the hot water that we’d been using to wash dishes, for example, I’d have to run the tap until it was cold again before I filled up the pot to cook. I’m not even sure if my dad knew why he did this, it’s just the way it was supposed to be done. But now I know that using cold water in cooking is important because of one thing: Lead poisoning.