If you've ever seen a fire hydrant gushing water onto a city street, then you might be able to get a good idea of the type of pressure that's behind the flow. But the minimum pressure required for a ...

Add Yahoo as a preferred source to see more of our stories on Google. Fire hydrant with water pouring into the street - Joanne K Hall/Getty Images If you've ever seen a fire hydrant gushing water onto ...

Fire hydrant with water pouring into the street - Joanne K Hall/Getty Images If you've ever seen a fire hydrant gushing water onto a city street, then you might be able to get a good idea of the type ...