India, Jan. 12 -- When people die in India's cleanest ranked city, Indore, because of dirty drinking water, shock and condemnation are justified. But this is not really about Indore, nor is it about water supply. It is about sewage-the excreta that we flush and forget every day. The problem is, we do not join the dots. Every city administration and successive government focus on water supply but ignore the fact that for every litre supplied, 80 per cent returns as wastewater. In our current system, this return flow or sewage is so expensive to intercept or treat that it is largely ignored until it resurfaces, mixed in our drinking water or polluting our lakes and rivers. So, unless we start obsessing about wastewater, clean-water security...