How to avoid pressure on the ecosystem and environment in urban areas of India?

I have read about a significant lack of the sewage network and capacity in India's urban areas as well as the treatment of waste water prior to discharge into canals, drains and rivers. I have been told that septic tanks are in use in fairly dense population areas and that the timely emptying of these is not always controlled.

Travelling around urban areas in the vicinity of Delhi, I noticed signs of what appears to be serious anthropogenic pollution in the canalised drainage in and around the city. 

The deficit in the waste water handling system is a huge issue with metros like Delhi. Delhi metropolitan area drains into the Yamuna, a major tributary of the Ganga.

Given the impressive achievements in the extension of water supply in India, this is only going to put more pressure on the ecosystem and water environment. How can we avoid this pressure on the ecosystem and water environment in Urban Areas and Metros of India? How is Mission Ganga going to approach the deficit in waste water handling?