Prince was playing outside his house when he accidentally fell into the sewer line through an open manhole and strong currents swept him away. His relatives raised an alarm, police said.
A search and rescue operation was launched but he could not be saved. His body was found nearly 100 metres away from the spot where he fell, the police said, adding that the body was shifted to the mortuary of a nearby hospital.
The boy's parents had gone to Bihar and he was staying with his aunt.