Penn has recently unveiled new 'Quench' water machines. The machines are basically like any Arrowhead or Sparkletts water machines, but do not have a 5-gallon bottle on top. Instead, they have an input valve that takes water through a pipe. The water is filtered, and therefore tastes better than the standard water fountain.
Another way to get great tasting water on campus is at Houston Hall. In the market, you can fill a glass full of water at the soda machine, and even get some ice. They won't charge you for the cup, which you can get in a 12oz or 16oz size. The water is also filtered.