Iphone 4 not charging. Is it the battery or the dock?

I got up in the dark in the middle of the night and I accidentally dropped my phone in the (clean!) toilet. Yes, I'm aware that I'm an idiot okay. I was super tired and groggy. Anyway, I put in rice overnight and it works fine now except that it won't charge. When I plug it in the battery shows the USB icon. I can also sync it with my computer. I think it just might be battery damage and I know I can fix/replace that. Any advice?

If you tried it on dock or using your computer its probably the iphonw that got the problem.