I live in Canada and tap water is drinkable, as a matter of fact, the government puts a little bit of flouride in the tap water so it cleans your teeth.

My wife and mom always tells me not to drink the tap water when it's warm/hot.

Is there something in the water that's bad for the body or is this a myth? (bacterias in warm/hot water vs cold)

Added info: The water is heated in the water heater which is in the basement of my house. It is a new water heater, only a year old. My house is built 7 years ago, which for a house it's not old. I don't know about the pipes though