The AQUS System has a great premise: reuse wastewater from your sink to flush your toilet! The systems gets tucked below the sink and works in conjunction with standard lavatory pipes. A single hose connects the reservoir inside the vanity to the toilet, eliminating the unnecessary use of fresh water. Apparently it's very simple to install, and can save 10-20 gallons of water a day.
Reservoir Dimensions: 13.5" D x 15.5" W 9.5" H. Unit weight 13 lbs.