We use a water fountain thing for our cat when we went out of town for a weekend back before we had too many other animals to worry about. He seemed fine with it. We left him plenty of food and the water fountain running (since he only drinks running water) and it worked out well. He is the only cat in the house and he eats free choice all the time anyway.

He did test his ability to come and go as he pleased once we returned. The constant "let me in"..."let me out"..."let me back in"..."let me back out" gets a little annoying! He always does it for a couple of days after we get back. Apparently, he didn't like being locked in the house for 2 days! Of course, if you have an indoor cat, that obviously won't be an issue.