There was a vicious labor dispute in progress at the time of the incident. Strikers sabotaged the plant.
See also https://www.bhopal.com/bhopal-tragedy-cause.html
Investigators believe the saboteurs died in the cascading failures caused by their actions.
Some two and a half years after the tragedy, UCC filed a lengthy court document in India detailing the findings of its scientific and legal investigations: the cause of the disaster was sabotage.
UCC’s investigation proved with virtual certainty that the disaster was caused by the direct entry of water into Tank 610 through a hose connected to the tank.
All of this was supported by hard evidence set forth in the presentation made by Ashok S. Kalelkar of Arthur D. Little, Inc. at The Institution of Chemical Engineers Conference on Preventing Major Chemical Accidents in London, U.K., in 1988.
Early accounts of the disaster that focused on the GOI’s theory that water-washing caused the accident subsequently were disproved.
Really! I never heard about that side of the story till now!