Also, you have to be careful when drinking too much water that you don't overdo it and cause water poisoning.
Just to let everyone know, ther's only been one case of water poisoning and it was during a water drinking compatition. the lady that died drank 9 gallons in under 1 hour. your really not in any danger of drinking too much water.
I've heard that you can increase the chance of getting a bedweting accident by drinking milk, but I haven't tried that yet. I've also heard that holding your pee and having cold during night also causes bedwetting (turning the AC, for example), so far it as only worked once for me, but it could be sheer coincidece. Most methods to artificially cause bedwetting has proven to be quite unhealthy, so my tip is "Don't".