19 years of free hot water all summer long.
We have lots of pipes in the attic, walls and ceilings. Any one could break or leak. That's what home maintenance is for. By running the drain pipes to the outside where they can be seen is the point to catching the leaks early. The tank was probably leaking all day while I was at work. Made no difference as the drains did their job.
My point; HWH's in the attic aren't to be feared.