Cut through a heating pipe. Having done DIY for the last 10 years or so, I've never managed it before, but now that one is ticked off. I was trimming off a floorboard in the bathroom with a multi tool and hit a pipe that runs across the joist.
I must have sat there for 5 seconds staring and swearing at the miniature fountain that was spraying over my landing before I did anything
Race up into the loft, scramble on belly to the storage tank thanking my lucky stars the hot water and heating have been off for the past 24hrs, wedge something under the ballcock so it can't keep refilling.
Try to wedge something into the F+E vents, realise that a) they are all gunky and b)I don't have anything suitable to bung them with (MUST REMEMBER TO BUY A BUNG KIT), parachute back down from the loft (thinking Jesus Jesus Jesus water comes out fast doesn't it?)
Bashed a screwdriver through the exposed ceiling where the majority of the water was collecting between the joists. Down into the kitchen that goes
Luckily I have the bathroom radiator off, so I used the valves on the pipes to empty into a handily placed bucket and pour the water straight down the toilet - a job made even easier because the radiator tails are joined to the old pipework by Cuprofit 90 degree bends, so I was able to swing them down and fire the water straight into a bucket.
Then I heard a faint crackling noise - that'll be the wet kitchen light then - flick the downstairs lighting circuit off and breathe.
Minimal damage, the ceiling has swollen and bowed ever so slightly where most of the water went, but it's still up, and everything else has survived pretty much unscathed. I'll try not to do it again though.