Please Help!

My son very kindly poured a whole bottle of mineral water into the door panel cavity in one of the rear doors! (The one like a cup with a screw in the bottom that you put your hand in to pull the door closed!)

Does anyone know if there is anything useful under it, or will it just work its way down and out a drain hole at the bottom of the door frame with the rain??

I just wanna know if it'll be OK or

Thanks

S