Let me lead off with it's not as bad as it sounds. We had a little flood but that's really giving it more credit than it's due. I've had floods (yes plural) in my dwellings before and this was peanuts compared to those. That and we had a healthy does of luck this time.
By the whims of my doctor's appointment book, Tuesday morning was when she could see me. So I opted to work from home seeing as the appointment was at a awkward time in the middle of the day and this was the most efficient thing for me to do. All goes as normal in the morning: the dogs get their walk and breakfast, Travis heads off for work, the dogs tuck into beds in the office and go to sleep while I get started working. The middle of the day rolls around and I need to head to my appointment.
While I'm backing my car out of the garage, running late (as usual), I notice that my car is leaving wet tire tracks and I notice a smallish pool of water under the dryer and towards the garage door. The garage door closes and I'm pulling away as I try to run through my head what day it last rained. Having ruled out rain water, I make a mental note to take a closer look at everything when I get back thinking perhaps the rubber hosing to the washing machine gave out and how we really should have grabbed those steel braided ones. But due to the aforementioned lateness, I really didn't have time to get to the bottom of it.
An hour later, I get back and the pool of water has roughly doubled or tripled in size. It's still well at the front of the garage. Our house, being pier-and-beam, was well out of harm's way at a good foot or so above the garage floor. So I start looking around for the leak. I shut off the washing machine hoses and still hear a leaking sound. I peak behind the washer and see that the drywall's wet but only to the right of the washer.
Now I start to panic because I'm really not feeling like crawling under the house to diagnose a leak and dreading having to rip apart the wall to fix it. I poke inside the cabinet below the utility sink and thank goodness (? :-/) it's coming from the exposed side of the wall. So I try to shut off the cold water tap to the sink. Nothing happens. Great. It's leaking from the joint between the nipple coming out of the wall and the shutoff.
All of this leads us to...
Lesson #11 in Home Remodeling (and/or Home Living-ship): What to do if there's water pouring into your house.
Shut off the water. Generally, any line to a faucet, shower head, toilet, or appliance comes with a shutoff valve for that line. If you can find this, shut it off and it does the job, great. However, water pouring into your house is one of the few scenarios where "using a sledgehammer to crack a nut" isn't really a faux pas. When in doubt, just shut off the main to the house and ask questions later. If you don't know where the water shutoff is, finding out as soon as possible is preferable to waiting until your house is flooding to sort this out. (Along these lines, finding your electric and gas shutoff and knowing how to turn them off might be handy too.) If your house is currently flooding, might I suggest stop reading blogs and instead, looking for the shutoff.
Open any and all taps downstream of the shutoff. So if you shut off just the line to the faucet, open the faucet. If you shut off just the cold water, then only open the cold water tap. If you shut off the line to the house, open any faucets inside the house or all of them. (Just don't forget to close them all before you turn the water back on.) You're trying to drain all the water and pressure from the pipes so the water pours orderly down drains instead of willy nilly into a wall or a cabinet or the like.
Now you may assess the situation and call the plumber if necessary.
But how did we fix this little sucker? We basically bought a replacement valve and installed it with a caveat. It seems the male threads on the nipple and the female threads on the valve just don't quite like each other. Perhaps one set wasn't tapped exactly right. Neither teflon tape nor pipe dope seemed to provide a tight enough seal. On a ( IMO hare-brained) idea from talking to the Dale guys at the neighborhood hardware store, a sandwich of pipe dope on the threads covered in teflon tape covered in more pipe dope finally seams to be doing the trick.