Chennai has a large number of lakes(many salty and marshy) with huge capacities. At least had. It would seem unbelievable for someone outside that even with all that the city has a drinking water problem. The situation is much better now. The ground water table in many areas is extremely salty/affluent and probably won't help much. Add to it the industry wastage that is discharged into lakes damaging the surrounding areas' ground water too. In these areas, it will take years of recharging and flushing to make the water even fit for bath.
I think Chennai's population would be much larger than 5 million if suburbs are included. But thankfully the distribution is spread across the suburbs which are far and wide into adjacent districts.
Thanks for the articles. But I would be happy if the storm water drains at least fulfill their one sole purpose. That is apparently too much of a favor to ask now.
For the long term, the only reliable water source seems to be the sea.
I hope
@nair is OK.