h2o by lemberthe regis from germany

Most often ecological devices need to be installed in place of former ones, making them expensive, waste-generating and work-demanding. In fact, unlikely to be installed.
H2O is a washbasin designed to adapt itself to most existing flush tanks. By combining these two devices one saves about 5000L water a year per user. All the clean water that is being used for washing one's hands is being recycled as 'grey water' - non drinking yet clean enough for domestic tasks - and used as the following flush.
In addition to the ecological aspect, it incites users to wash their hands in the toilet room, preventing the apparition of germs on the door handle.

Installation is made simple by the semi-elastic material that enables the lower part to stretch around the tank, and the laces that make it fit perfectly. The mechanical part is just as easy: by conserving the one standard item present on all flush tanks - the arrival pipe - only the floater and the top cap are to be removed. The new system simply requires one screw to be installed.

The flush handle is located in the bottom of the basin; once pulled, the flush is activated, and as soon as the floater is down water flows through the tap, beneath the flush handle and back in the tank. A waterproof seal can also be used cover the handle, leaving water in the washbasin just like in a bucket for domestic use. Even water dirty from a thorough toilet-cleaning activity is good enough for flushing.