India, June 8 -- Delhi's water crisis has now entered its third week. The problem has reached such levels that excavators have been pressed into service, digging into the Yamuna to draw pooled water to two treatment plants. The river has fallen five feet below normal; the plants are running at 15-40% below capacity, and residents in many localities are queuing up at 4am for tanker-delivered buckets.

At the heart of the problem is a demand-supply mismatch. During a punishing summer, the city needs 1,250 million gallons of water daily but gets 250 mgd less. A 20% shortfall is bad, but it is made worse by ailing infrastructure and shoddy design which leaves colonies at the tail end of the distribution system without water for days; many who...