The pipeline burst took place near the Sanjivani society in Govandi suburb, sources in Brihanmumbai Municipal Corporation told PTI.
The deceased was identified as D Hajare, a 60-year-old resident who lived at the ground floor of the housing society.
People sleeping on the ground floor of the building were caught unaware as water gushed into their homes after there was a crack in the 24-inch pipeline.
BMC officials said they would ascertain if the building was authorised, and how it was permitted to come up in proximity of the mainline.