Some time ago, a customer came into the shop with his rather expensive PC which had been submerged in nearly a foot of water for several days following a flash flood.
It's a shame I didn't think to take a picture, but you could quite clearly see the watermark inside the case.
Fortunately the bloke had kept his wits about him and not tried to switch it on immediately.
He left it to dry in a warm place for a few weeks, which was when he brought it to me.
Incredibly, it booted up nicely at first. Gradually it began to lock up as if breathing it's last breath, at which point we saved his data and he more or less dumped it on me for salvage.
That must have been about two years ago and I'm pleased to report that the hard drive still works perfectly, the GPU died about a month ago and the 600 watt psu is well handy.
Useful to know if such a calamity should happen to anyone.