The plumber arrived this morning to see if he could find and repair the leak in our bathroom.  After a few hours of chipping out concrete, he located four pinhole leaks in a three foot section of the hot water supply pipe.  A couple hours later and we supposedly have no more leaks.  We do, however, have a large hole in the floor of our bathroom:

We can only guess at what caused the leak.  The plumber said that the copper pipe was touching the steel rebar in the concrete, so it’s likely that the cause was corrosion due to dis-similar metal contact.  I’m kind of surprised, though, that it took 28 years for that to show up.  I would have thought that the corrosion would be faster than that.  What’s scary is that this kind of thing often causes pinhole leaks to appear along the length of the affected pipe, so it’s possible that we could have other leaks that we don’t yet know about.  We’re going to leave the hole there for a week or more to see if we discover more water.

The plumber mentioned something that I hadn’t even considered:  homeowner’s insurance.  He said that most insurance companies will pay for discovering the leak and for putting things back the way they were, but won’t pay for the actual leak repair.  If that’s true then we should be almost fully reimbursed for the plumber’s time, since it only took him about 30 minutes to fix the leak after he found it.  I wonder if the insurance will pay for a new cabinet and new floor coverings, too.  You can bet that I’ll be on the phone tomorrow to find out.