I would consider 2 options:
* Does insurance cover you? Copper pipes shouldn't rust through - there's no reason that it should fail AFAIK. In which case each incident is covered by insurance. It may not have had corrosion inhibitor put in though
* If the system is very old then the inspector should have inspected it and let you know. Consider his liability here. You paid him to inspect the house and fabric. Should he have mentioned the state of the plumbing?