I don't underestimate the power of water - I've used UHP water blasters at work and seen it cut through concrete. Not pointing the nozzle at close range into any seals, bearings etc is a no-brainer. I'm just interested to find out if anyone has used them with a bit of common sense and still had it all turn to shit, or is it one of those statements that everyone assumes is true but no one has ever confirmed.
A bit like how a swan could break your arm yet no one has ever met anyone who has suffered from swan-related limb injuries...