The boy, named Amit, drowned after he fell into into a drain at Rajiv Gandhi Colony, in Dharavi, a sprawling slum colony in the heart of the city, an official said.
The incident took place when Amit and his brother were playing near the drain, he said.
After being alerted about the incident, police rushed to the spot and pulled out the boy from the open drainage.
He was rushed to Sion hospital, where he was declared brought dead, the official said.
In a similar case, 18-month old child named Divyanshi fell into an open manhole in suburban Goregaon on Wednesday night. The Municipal Corporation conducted the search operation for about 48 hours, but called off the operation after searching for 10 kms of the drain line.
On Monday, Dindoshi police filed a criminal case under section 304 A (causing death due to negligence) of the IPC against the officers and staff involved in supervision work of the drainage on the basis of a complaint filed by the child's father Suraj Singh.
Singh, talking to reporters during the operation, had accused the Brihanmumbai Municipal Corporation (BMC) and other forces of negligence during the search. He had claimed the civic body did nothing about the open gutter despite constant reminders from local residents.
On Saturday also, a 12-year-old boy died after falling into a water-filled pit, dug for the construction of the Coastal Road, near Worli.
The boy, Bablu Kumar Paswan, had fallen in the pit near the Worli Sea Link on Friday, the police said.