Look out of the window the next time you travel by road or by train anywhere in India. Hit a human settlement, and you will see, heaps of plastic coloured garbage apart, pools of dirty black water and drains that go nowhere. They go nowhere because we have forgotten a basic fact: if there are humans, there will be excreta. Indeed, we have also forgotten another truth about the so-called modern world: if there is water use, there will be waste. Roughly 80 per cent of the water that reaches households flows out as waste.