About 2:30, Tara (robot_grrl) called and let me know of the problem. She was a bit worked up about it, and had me thinking that everything we had stored out there -- a LOT of stuff is in the garage since this house is smaller than the one in Bartlett and we didn't expect to be living here for even this long when we moved in -- was a loss.
I was able to give her advice of limited use (she couldn't turn the shut off off because of where it was located) and called the rental agency (probably the only advantage of renting is that we didn't have to figure this out entirely ourselves) to deal with the emergency.
Unfortunately, the northbound trains were at 2:42 (which by coincidence was when I got around to looking at the schedule to see when it was) and at 4:05. So I waited around until I could head over to the other building and catch the shuttle for the 4:04 train.
When I got home, the plumber had been there, and could do little more than shut off the water. Tara and Derrick -- the latter being less help than he should have been -- had gotten most of the boxes, which were mostly books and CDs, out of the water.
After I got some replacement banker boxes (most of what we had were in banker boxes -- consistent size and strong enough to hold books), I spent a couple of hours repacking books and determining which were losses.
In addition to the books, my desk (not a great one, a 10-year-old press-board Office Max product) and some shelves are a loss. We also have some pictures that were in boxes that got wet, and have yet to assess them (or even get some of them into the house for assessment).
Today, in addition to working from home and waiting for the replacement heater, I need to go through the books that we've determine aren't salvageable, get their ISBN information (or other unique identification) so that we can file an insurance claim against our renter's policy.
Since the water heater was less than 3 years old (installed in December 2006, according to the date written on it), we are pretty sure that both us and the landlord have a claim against the manufacturer. But I think I'll let AAA deal with that fight rather than us. I just hope that AAA can go directly to the manufacturer and doesn't have to first go after the landlord and have them add our claim to theirs. But that is legal and insurance stuff and I have no idea how that works.
If anyone knows of a good website for getting value estimates on books, many of which are old and out of print (including quite a few 20-25 year old text books), I wouldn't mind the reference.
For what it is worth, neither Tara or I had thought too much about storing this stuff in the garage. First, as I said, we hadn't expected to be living here this long, but the house took longer to sell and didn't sell for as much as we first expected, so those plans changed.
But, at least I had no personal experience with this kind of catastrophic water heater failure (the top seam seems to have given out), and tend to think of flooding like this as something that happens in basements after heavy rains or snow melt. I guess this is another case of "live and learn"