Some time ago my daughter accidentally dropped her phone in the bath! She dried it, best as she could and then went over it with a hair drier - apparently the worst thing one can do! As the 'phone was dead as the proverbial doornail, she left it and continued to use a spare.
About a month or so later, she decided to take the 'phone to the local Apple store to buy a new one (it's a 4C and well out of warranty), and hoping she could get something off the purchase price for the old one. She explained the situation. The genius tried to switch it on and, lo and behold, it booted up! The genius had a look inside and said there was some evidence of water ingress and it couldn't be guaranteed that the 'phone could fail again.
Approx 2 moths have passed and the 'phone is still working fine! So, the moral of this story is "if you drop your 'phone in water, don't give up hope - there may life in the old dog yet! 🙂