India, Sept. 24 -- Around four in every 10 households in Delhi, most of them in unauthorised colonies and slum clusters, are still not connected to the city's sewage network, according to Delhi Jal Board (DJB) estimates. Officials said that this the gap remains perhaps the biggest challenge to the government's target of cleaning the Yamuna within the next three years.

Even as the Yamuna clean-up has become a key priority for the Delhi government, with efforts focused on expanding wastewater treatment capacity, data submitted by DJB to the National Green Tribunal (NGT) showed that more than 1.65 million - 41.3%- households are not connected to the sewage network. Sewage from the remaining 2.35 million households is currently being carried...