Eye liner on the water line just does not last long. One option is to keep applying it while you are out but that is fairly annoying. My easy advice:
To keep eye liner on your water line, my tip is to go over the eye liner with eye shadow the same colour as the eye liner.
Make sure you aim the eye shadow well because it’s uncomfortable for a few seconds if you get it in your eye. It’s like keeping your foundation on by applying face powder afterwards.
The water line can obviously get quite watery being part of the eye, but eye shadow dries the water line letting the eye liner stay longer.
I wouldn’t suggest doing this daily just because the water line does still need to breath. I usually do this when I go out clubbing or special occasions.