Large-scale LEED projects sometimes install massive systems to treat and re-use grey water (water from sinks that has been used for washing, as opposed to sewage waste, which is termed black water) for flushing toilets. Now, you can do the same thing in your very own home!

The Aqus system collects the water from a bathroom sink and filters and disinfects it before it gets re-used as flush water for an adjacent toilet. (There is nothing that would prevent this from being used in a large-scale LEED project either.)

"Our system is expected to save between 10 and 20 gallons of fresh water per day for two person bathrooms with normal activities. This represents between 3,650 and 7,300 gallons of fresh water saved per year. An equal amount of wastewater cost is also saved." This would mean an annual savings of $40.88 to $81.76 (based on an average rate of $5.60 per 1,000 gallons) from using a device like this.

The Aqus system can be retrofitted to an existing toilet without great difficulty (the company likens it to the difficulty of installing a new toilet and/or an over-the-stove microwave oven). It can be connected to a standard 1.6 gallon two-piece toilet.