Oil mill owner Sanjay Das (46) died when he tried to rescue Rahul Shaw (17) who was reportedly asked by him to clean it, police said.
"When Rahul fell into the reservoir Sanjay jumped into it to rescue him. Hearing them screaming locals rush to the place and managed to pull out the teenager but failed to rescue the mill owner," a senior Kolkata Police officer said.
A team from the force's Disaster Management group rushed to the place and pulled out Sanjay, who when taken to a local hospital was declared brought dead.