New Delhi, Jan. 26 -- A British biologist has triggered widespread debate on social media after posting a video in which he conducts a water quality test on the river Ganga and explains his findings. The video was uploaded on Instagram by Jeremy Wade, a well-known British television presenter, author and biologist, best recognised for hosting the show River Monsters.

In the video, Wade carries out a basic water test using a container treated with chemicals that react to contaminants by changing colour. Explaining the process, he says, "Pink means the river is clean. Anything else spells trouble."

To set a benchmark, he first tests bottled mineral water. The sample turns a darker pinkish-brown shade, which Wade points out is the colour e...