Should you put eye liner on the bottom water line of the eye?

That is a decision that would need to be completed by you. It is okay to place eyeliner on your lower & upper water line ( never liquid ). But bare in mind that there is a risk of bacteria getting into your eye which can cause sty eye. If that is something that you don't mind taking the risk at, then go for it! Applying eyeliner to your lower water line can create the illusion that your eyes are bigger or smaller. If you decide you want to apply a natural or white eyeliner it can make the whites of your eyes appear brighter.