Today we were supposed to head out to Mum and Dad's for a visit, but when Sabriena looked out the window this morning she noted that there was a bunch of water on the driveway. I shrugged and said "it's probably condensation" since the top of the car was covered in it, but she looked again and it was red.
"That's coolant," I thought. Sure enough, the heater tap that's been dripping for a few weeks now (I was going to replace it nearly two weeks ago, but SuperCheap didn't have any in stock because they'd been apparently stolen) looks like it's let go. Under it is completely saturated, there's no coolant in the overflow tank. Damn it.
I filled it back up with some demineralized water and drove to get a new one. They had them in stock, thankfully, so I bought one and another couple of gallons of water to refill it - I'm damn sure not putting any coolant in it until I know it's not going to leak out!
I then spent the next couple of hours doing it. It's not a terribly involved job: easy enough to get to, four house clamps and it pops right off as it's only clipped to the body. Unfortunately though, because of the heat the fittings crumbled apart as I tried to remove them. I went to remove one piece of hose because bits of crumbled plastic fell into it, and the plastic "tee" fitting it was connected to crumbled as well. I thought I was going to have to chase leaks all over the place, but I got that fitting off without further incident.
But how to replace it? The car can't go anywhere. I had to get my bicycle out of the shed and ride it up to get a replacement, at a cool twenty bucks and in ~36C heat no less. I got home, replaced everything rather trivially, refilled it with water and bled the system out. Took it for a test run, and everything's dry, so I shut it down for the night.
Update: The next morning, everything's still dry, the coolant level is about a CM down from the cold-fill line. I left it there, and on Tuesday morning when we took Duncan to school it's still there, so filled it to the cold-fill line. No more leaks, for the time being.