Nokia :: 5800 Xpress Music Rapid Battery Drain ?

I have a Nokia 5800 xpressmusic mobile and its about 7 months old , I charge up the phone and the batery lasts between 6-8 hours with very little use ? the phone is just draining the power from the batery . At first I thought batery dyeing so I put another one in , charged it up and the same happened again,About a 2 weeks ago it did get wet fell in the sink and I dried it out and waited a few days befor I switched it on and it worked perfect no problems until a couple of days ago. I can put batery in and charge it switch phone on with no problems , I even took the batery out to see if the batery was dyeing on its own with no problems put it in my friends phone and it lasted as it should , so is this a software problem in the phone or is it earthing or something to cause a drain?