India, May 21 -- On a hot afternoon in Dichaon village on the outskirts of Delhi, one can see lush green rows of cauliflower and jowar (sorghum) from a distance. But as you move closer, a strong stench hangs heavily in the air.

Just 500 metres from the green expanse is a drain choked with untreated wastewater and solid waste. What is not visible though is that through an underground pipe, the same polluted water is irrigating the fields, feeding the crops that are almost ready to be harvested and sold.

A few metres away from the fields, a worker, Mitthu (he only uses his first name) is preparing his afternoon meal inside a small shed built at the end of the cultivated land.

When asked about the source of water used for irrigation, Mitt...