Grow your own vege AND fish at the same time! You'll use LESS water, produce MORE vege two to three times faster (because fish poop makes for happy healthy veges) and have your own supply of healthy, "organic" fish all year round.
5 DIY Backyard Composting Solutions - here is a stacked version that doubles your capacity with the same footprint. A black barrel would warm up compost for quicker breakdown and blend for better eye appeal.
Hot water tank heated by wood burning stove. From Teach Nollaig, Tiny house in Ireland. Could be improved by adding a small sterling engine to power a circulation pump, allowing the hot water tank to be up higher [improving pressure]. Also INSULATION!