Yuck!!

We have a glass of water in the master bath that we always fill up, and it is the main cat watering hole. They rarely ever drink from the water bowl by their food dish.

You most definitely have been sharing water with the cat for a long time now. My cat does that ALL of the time. We have just gotten used to it because we never know if she has weaseled her way to it or not. She likes to knock over the glass all of the time too. That irritates me sometimes, but the water drinking does not really bother me so much.