All over the net you can read the claim that 80% of water used to wash hands, brush teeth and shave goes down the drain. While the amount wasted this way is dwarfed by the amount wasted on carpet grass, the amount is significant enough that restrooms in commercial facilities all over our region use automatic sensor faucets.
These automatic faucets require power and a change in fixtures. The fixtures can cost hundreds of dollars. But there is a mechanical alternative for less than $20 per faucet. The Smart Faucet and Automatic Faucet Control feature a replacement for the screw in aerator which all modern US faucets have. A rod extends from the replacement aerator. The valves on the faucet are set open. When the rod on the aerator is pushed, water is released. When pressure on the rod is removed the water stops.
While the devices look unusual and have not been designed with beauty in mind, the low cost and water savings may let you learn to love them. In addition to saving water the devices prevent cross contamination and make it faster and easier to wash up. It also benefits those with grasping, twisting, turning and gripping difficulties. Because the devices allow the faucet valves to be left in an on position the sellers claim that the faucet valves will last longer.