Found this little gem today 12-Volt Overland H2O Systems. I couldn't find anything on this site after a quick search, so I thought I would post it up. This looks like an awesome solution for anyone that doesn't want to run/build on board water, or if your getting tired of picking up 20L can every time you need water. It runs off of the 12V outlet, and comes as a DIY kit, or assembled. More info and instructions here.