Water supply in Delhi was hit after ammonia levels rose in the Yamuna river, the Delhi Jal Board said. Post Diwali, the level of ammonia in the river rose to 2.2 ppm (parts per million). The permissible limit for drinking water is 0.5 ppm. A toxic layer of white foam developed on the Yamuna giving the river an ethereal look. BJP MP Manoj Tiwari accused Delhi CM Arvind Kejriwal of implementing a ban on Chhath puja to hide the impact of pollution in the Yamuna.