How can you reduce water consumption with little effort in public buildings? With a cheap, small tool. Usually a lot of water runs unnecessarily when washing your hands, because the handle of the mixer is in an awkward position.  To wash ones hands lukewarm water is usually enough. So if someone before you has used  hot water, you must first adjust the lever and let water flow until you have cold water.

A built-in spring turns the handle via a timer - i.e. after a certain time - back to the (freely adjustable)  basic position: cold or medium.

A low-cost accessory that can be easily retrofitted into existing buildings.