There will be some mineral and calcium deposits on the screen from the water, when heated I don't know what that will do to you, mind you it's only a small amount. The actual screen, they said best. It's probably not the best material and when heated probably isn't good for you either. My local head shop has a gumball machine which has little containers of screens, I think 10 per container. It costs a buck, it's easily worth it.