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!
Aquaponics 4 Idiots - The Idiot Proof Way of Building an Aquaponic System
Using a rain barrel can save you a significant amount of money in a season. For each inch of rain that falls on 500 square feet of roof, you can collect 300 gallons of water to use in your garden, or your lawn. If we ever got rain.