Ben, the response from Ron was right on the target, but I would replace the copper. At this point in its life, it is trouble. Ron's suggestion about a valve (of the same material as the pipe) ahead of the fresh water in-let on the water heater shows good forethought, but put one in also ahead of the toilet: those two are the source of most (but not all) water leaks. A valve you can get to on any supply line is worth several times its weight in gold when the fixture it supplies starts to leak.

We are all in there for you!

Donald Kribbs NOW - Wbcci #2875!!!
(will be in the new Directory)