One normally thinks of copper as a stable, rather non-corrosive metal. Copper plumbing used for domestic hot or cold water lasts for years. Unfortunately, in instances copper pipe has been in service for only a year or two and failed.
Water leaking from the outside turns of elbows is often the first evidence of failure.
Obviously, softened, circulating domestic hot water loops are prime candidates. Avoid zero-hardness soft water. Lower the water temperature to the minimum needed at the point of use. Lower the flow velocity so return water is at least 10 degrees lower than supply temperature.