How can we convince (in a compelling way) people to consume less water in public buildings? With an optical effect as a catcher. In most cases, the faucet is turned up too high when washing ones hands - a small jet of water would also suffice. An LED colors the water jet when adjusted correctly, a green-water tap. A pretty sight, a practical use.
Note: this accessory is not new, but the way in which it is used is.
Update: The current for the LED is generated by a small turbine inside the faucet. The turbine is powered by the water jet.