The incident took place last evening when the victim identified as Krishna was playing in a ground near a water tank built by Kanpur Jal Nigam, a police spokesperson said.
A few months ago, a pipeline of the tank had developed leakage leading to accumulation of water in the ditch.
The body was found floating in the ditch by the boy's parents late last evening following which locals staged a protest but were pacified by the officials, the spokesperson said.