The incident took place on 2 February, when Suman Sardar, Farzem Sheikh and Hashi Sheikh were working on a Kolkata Metropolitan Development Authority (KMDA) project near the Kolkata Leather Complex.

The KMDA said the workers were building a 3m-deep manhole for a sewer, not repairing or cleaning the current structure.

Indian English language paper The Telegraph says the incident took place four days after the Supreme Court outlawed manual sewer cleaning and scavenging in six metro areas, including Kolkata.

The National Human Rights Commission of India said local authorities must use new ways to clean and repair sewers, such as robots. They have banned the use of hazardous products and increased the use of protective and safety equipment.

https://www.globalconstructionreview.com/three-workers-drown-after-inhaling-toxic-fumes-at-india-sewerage-project/