tearing up my foundation to my sewer-line on the interior showed me my 1970s cast iron pipe was literally rusted to dust in 3 or 4 places. The plumber said there must be some mineral in the ground that is working on the cast iron. The part from the house to the sewer may never break but the indicators I have seen first hand tell me they will someday.

That said I don't know anyone whose water line broke.