Lived in Chennai for three years. Just few weeks back I relocated. One thing we must remember that TN hardly has any river that is filled with water, for the whole year. All these rivers are rainfed rivers. And for more than seven months, there was no rain. Sea water purification is way forward without a doubt but whenever it rains, govt has to come out with a plan to reserve it as much as possible. Hope the city will bounce back to normalcy soon.