Despite what you may think, water actually isnt a very good conductor. Shorting you phone would be harder than you think. When people say dont swim or take a shower during a lightning storm, the reason is because the salt on your body IS a good conductor. When the salt mixes with the water THAT is when water becomes dangerous... I think your phone will be fine
Also, I have heard that if you put your phone in the freezer it will also help. No joke. My friend fully submerged his KRZR in water, put it in the freezer and it worked just fine. Dont ask me how as I have no clue...