Area’s of screen sometimes unresponsive after water damage?

Basically I dropped my iPhone 6s down the toilet and it was probably in there about 10 seconds before I realised and took it out. I took it out the case and dried it off and tried to turn it off however this took a while because Siri was going mad as the home button was messed up. I couldn’t get it in rice straight away but once I was home I put it in a bowl and left it for just over 48 hours. Now, I turned the phone on and it seems to be working except for the screen which is being temperamental. The top right hand corner seems to be unresponsive to touch, as well as the bottom of the screen when I try to swipe up however this isn’t an issue all of the time and sometimes it still works. It also has some strange diagonal lines where the screen still works, it’s just that it’s a slight different colour but this doesn’t bother me too much. Does my screen need completely replacing? I am just unsure seen as sometimes the screen will actually work! I think the battery is also draining faster than normal so I believe that will need replacing. Does anyone have any suggestions? Thank you in advance!!!