Grats on the 1337 post Andy.
Firstly, why do you want to clean your Deck by washing it like this? Personally I would try to clean it using rubbing alcohol and compressed air first unless further cleaning is absolutely necessary.
In regards to washing your keyboard: it should not harm it if done properly. Please take this as a suggestion and not an endorsement of what to do (i.e. this should work but may void your warranty). What we recommend is this:
1. Disassemble your Deck using the instructions
found on our main site. You should also remove the USB cable.
2. Place it in the dishwasher with no detergent (and no dirty dishes).
3. After washing, stand upright and place a fan in front of it for at least 24 hours. The more time the better, the warmer the area the better.