Most people think of rice when their phone comes in contact with water. The truth is rice does not do much for a water damaged phone. The best thing to do when your phone comes in contact with water is to disassemble the phone and remove the battery as soon as possible. Then clean the motherboard and other parts with 90% or higher isopropyl alcohol and a small soft bristle brush, toothbrush works well. Doing this helps remove minerals left behind by water when it dries. If the minerals from the water are not cleaned from the motherboard and other parts then corrosion, or possible shorting may end up damaging the components inside the phone.
Cleaning with isopropyl alcohol may help fix your issues with the digitizer not functioning properly. As there may be some corrosion present on the digitizers cable end or its connection on the logic board leading to a poor connection.
If cleaning with isopropyl alcohol does not help you may need to replace the digitizer eventually.
Also there are many instructional videos on sites like YouTube that will show you how to clean your water damaged phone with isopropyl alcohol. Hope this helps and best of luck.