In Japan, the sink is not next to the toilet: it is above the tank. The system works like this: clean water comes out of the faucet integrated into the top part, you wash your hands with it and, instead of going down the drain, that same water falls directly into the cistern to be used in the next flush. The result is that a single fixture serves two functions without wasting a single drop. This closed-cycle design has been standard in Japanese homes for decades and allows the country to save hundreds of millions of liters a year, in addition to optimizing bathrooms where space is minimal. It does not require additional plumbing, does not take up extra square meters, and does not depend on any costly technology. It is the simplest solution to the most urgent problem, and the rest of the world still has not fully understood it.
