Dropped iphone in bath, battery issues?

Okay, so i dropped my 16GB iPhone 3GS in the bath, oops. At first the screen died, so i left it to dry on the radiator. The phone then started working after 2 days, but now the phone seems to shut off every so often, and change the battery percentage, so it may start at 70% die and go to 30% and then die again and go back to %70. The other issue is that when the phone is on charge the battery dies every few minutes, what can i do?

Take it to your nearest store, you may just need a new battery or the problem may be the phone itself. If its under warranty don't say you dropped it in water because you could get a free phone possibly.

You can try putting the phone in a bag of rice and leave it over night. I don't know if this will work because you would have to try doing this almost immediately. But still worth a try.

Replace the phone.

Anything else will be hit or miss.

Likely you have some bridging on circuit traces inside the phone. You could do this (assuming you have all materials ready):
- pull the battery and have a new one ready
- dip into deionized water 5 - 10 times, submersing as long as you estimate you did in the tub
- dip into the purest isopropyl alcohol 2-3 times, same submersion time, new "vat" with each dip
- store it in the oven set on "warm" about 150 °F

Let it cool for several hours, install the new battery, charge per instructions for a new battery and see if it works correctly. It is possible the deionized water will do *more* damage, and the alcohol will damage some plastics. So that is why I say to replace the phone…