water makers
Keep in mind that even the small ones suck some power when operating so if you haven't already, you'll probably need to upgrade your electrical system. Space will most likely be an issue so consider one of the modular units where the pump and membrane housing are not mounted to each other. This will give you some flexibility mounting wise.
Water makers do not like occasional use as water left sitting in them will decompose/grow things and damage the membranes. If you don't plan on using it regularly, be prepared to flush and pickle it if you don't expect to run it for a while.