I was able to stop the flow by closing off some valves. My landlady came by to take a look, just as I was calling a plumber -- "Water Heaters Only, Inc", from the Yellow Pages, seemed like a good bet (I looked around online, and found a site that validates the permit number listed on the estimate sheet, and a reference to them here; I still sorta wish I could find some sort of Better Business Bureau or CR site that evaluated them) -- and then went off leaving me to take care of things, agreeing to cover the costs. I had time to run into work to get my computer and get back to the house before their technician came by. He took a look and determined that the tank could not safely be repaired, so the whole unit needs to be replaced. Which would be easy, except that apparently the city has tightened some rules on how they have to be installed -- the pressure release valve has to vent outside the building, in a location where it's unlikely to scald somebody either randomly passing by, or messing with the heater. Currently, the valve vents towards the feet of anyone standing next to the heater. Since WHOI is a licensed contractor, they're legally obliged to meet city inspectors' standards. The tech said he personally thought it'd be safe to just add a bit of pipe so the valve would vent onto the floor of the main part of the garage, so the water could flow out towards the garage door instead of pooling in the storage unit, but that Palo Alto's inspectors are sticklers about this stuff. (Apparently contractor inspection fees are a nontrivial source of revenue. Cue my various libertarian friends noting that housing costs in CA have been driven up by poorly-run regulatory schemes.) Anyways, including the work of running a bunch of pipes and building a new platform to stand the heater on (did I mention that the current heater is standing on a rickety-looking wooden platform, the integrity of which was probably not improved by overnight marination?), the estimate was $1534. Eep.
The landlady made some calls and found a friend-of-a-friend who was willing to make the replacement without doing the extra work to bring things in line with the city code for $650. But that would, as I understand it from WHOI, leave her liable for any damages caused by problems with the heater. And I think the not-up-to-code issue also means that if the water reached high enough to soak the bottom of the couch I have stashed in there, my renter's insurance may not cover it, in which case I'll take it out of the rent... After some calling back and forth with WHOI and the landlady, they agreed to knock a hundred dollars off the price and provide a slightly better heater than the one that's being replaced. That, plus the fact that they provide a warranty (one year on the pipes they're adding, and six years for the heater itself) and a guarantee of city enforcement against them if they did poor work (like, uh, installing the heater with its release valve aimed at your feet and a rickety platform supporting it?), got the landlady to agree to the higher cost.
Anyways, they'll be over early tomorrow morning to do the work. Between today and tomorrow, I've had to take a day's vacation for this. I'm hoping that they can run the valve discharge out the back wall, into the space between the townhouses and the wall bordering the Jack-in-the-Bα parking lot. That would actually lower the price, since the estimate was for if they had to run the pipe all the way around the garage and out the front wall. It'd also mean not needing to drag the shelves and other assorted stuff in the garage out away from the walls.
After getting all of that stuff arranged, I finally set about figuring out how to get the pool of water out of the storage space without first moving out the stuff in there. (I can't move the couch by myself, and even if I could, moving stuff out would require tromping around in the puddle.) I was on the verge of going out and buying a shop vac, when I realized that the shape of the puddle put its deepest point right near the doorway, so I ended up just spending half an hour standing there with a broom, encouraging the water to flow out the door. (Sorta like rowing. You'd think, with it being relatively small motions, and only resistance from maybe an inch and a half of water, that this wouldn't be that bad, but after the first ten minutes or so, you start to notice that it's work...)
Utterly unrelated: Forget Ray Charles, Bobby Darin, and those other singers -- when do we get biopics about this guy and his dad? Fascinating stuff...