Sounds simple but remove it from the water asap!!! You really don’t want it soaking up water for more than 20 seconds. Now the most crucial step, remove the battery whilst its still in th water if possible! Most damage comes from electricity passing through wet circuits, if you remove the power source quickly this will not happen! Next take out your SIM. Now to dry your phone place it on a towel or other soft absorbant material to gently dry out what you can of your phone. Then place it on a fresh towel and place the towel into your airing cupboard, boiler room or on a radiator. Leave for a few days to completely dry out your phone. Test your phone. If its working then great! If your still having no luck try using the hair dryer on it for a few seconds. I would not recommend this as your first drying out method as sometimes the heat can damage the phone even more. But if you really can’t get your phone to work this may work as a last resort.

Good luck!