apocalypse bunker made from a former missile-silo, these could be a good idea,purchase them around the country if your a millionaire and have nice rest points for you travels during the z end of days lol(also can be used as an minecraft house I'd
you could add some fish to your water reclamation tank for a small aquaponics system. Grow a few plants to feed the fish and this forms a closed system. There is no need to fertilize, the fish do it for you! Permaculture at its finest!