Creating an automated grey water and hands-free faucet system for $40

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50 shades of grey… water.

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The average American flushes a toilet in their home five and a half times each day, with the typical toilet putting down around two to five gallons of water with every push of the lever. That means, each person flushes away just about 25 gallons of water on their own, equating to 4.8 billion gallons as a whole daily. Given that more than 57% of the country, and 99% of both California and Nevada, is enduring drought conditions, reducing the amount of water that a toilet wastes can go a long way in conserving that good ol’ H2O.

For those who rather not abide by the “If it’s yellow, let it mellow” motto, which has been the go-to rule for selective flushing for decades, this recent Hackaday Prize entry will certain come in handy. That’s because Maker TV Miller has developed an Arduino-powered, “hillbilly cheap” grey water recovery and hands-free faucet system for less than $40 in components.

Unfamiliar with grey water? This term refers to gently used water from a bathroom sink, shower, tub and washing machine that has not come into contact with feces and other forms of waste. When collected using a separate plumbing system, domestic grey water can be recycled directly within the home and utilized either immediately or processed and stored. While this form may not be safe to drink, it does provide the necessary fluids for washing and flushing toilets.

This DIY project, which took no more than four hours, consists of a simple grey water reservoir that the Maker created using a zig-zag network of PVC pipe underneath the sink. This way, whenever someone uses too much water, it simply goes back into the drain in P-Trap-like fashion. Flushing the toilet triggers a 12V solenoid and 240L/h water pump that is tasked with refilling the tank with the reused grey water. TV Miller also employed an Arduino Uno (ATmega328) along with a 16×2 LCD display to reveal the volume of H2O saved and seconds of operation.

You’ll even notice that the Maker added a nice touch the control box, which we’re sure our friends at Hackaday loved just as much. Watch the system in action below, or head over to its official Hackaday.io page here.