Sewer gas deaths: the science behind fatalities and protective gear

In July 2025, the Government informed the Rajya Sabha that 377 people had died between 2019 and 2023, while they were involved in the hazardous task of cleaning sewer and septic tanks.

- 

Just a few years ago in Chennai, at a prominent mall, a worker lost his life while cleaning a septic tank -- and this is despite manual scavenging being banned in the country. Ironically, two national surveys (in 2013 and 2018) claimed that manual scavenging no longer existed in India. The challenge therefore, lies in identifying manual scavengers, as their work is often informal employment or outsourced contracts. While there is undeniable sociopathic negligence with regard to this practice, the conversation often focuses solely on its sociological aspects. It is also critical however, to understand how sewer gases are formed, their impact on the human body, and the mechanisms of fatality and consequences of exposure to these gases.

What is sewer gas?