> Sorry to be boring but a simple timer seems more sensible.

Not all projects are about being sensible. This is "hacker" News after all.

  > And kitty needs water.

Water and food have different needs; an automatic water fountain like http://www.amazon.com/Drinkwell-Platinum-Pet-Fountain-168oz/... keeps a pool of water fresh at all times, without needing to dispense a particular measure of it.