Dropped my Moto X in a sink full of water last week.
1) Turned it off and on after drying it (mistake--don't do that) and the cellular signal wasn't registering;
2) Let the phone sit in a bag of rice overnight (just six-seven hours), turned it back on and it seemed fine, but after a few minutes, the cellular service cut out again.
3) So I put it back in the back of rice and left the phone in there for a total of almost 48 hours.
Took it out, and it was fine. Like nothing happened. I think the moisture in the phone was ruining the cellular service. Once it tried, everything seemed normal again. It has been almost a week and the phone has been awesome--like nothing happened.
My recommendation if you drop it in water is to be patience and let it dry.