While the Abisko Washbasin does a fine job of encouraging water conservation, I’d one-up this design and go a bit further. You see, the Abisko Washbasin uses an angled design which allows wasted water to flow its way down through a drainage grill installed in the floor.
If you really wanted to encourage people to conserve water, you have to appeal to their common traits, such as laziness. Remove the drain grill and allow the wasted water to just splash all over the damn floor. I guarantee that people would waste a lot less water just because they are too lazy to clean up their wasted mess.