Washington, DC, the capital of the world, ooops, I mean the USA, has water mains that date to pre-war days. I'm not talking about WWI or WWII. No... the pipes were laid just before the U.S. Civil War. The local water company does try very hard to update the system, but digging and putting down new 3-foot pipes around the entire city taks time. They do use extra chemicals to treat the water.... but I would never drink the tap water in restaurants/hotel/home in DC.