While searching the infant, the mother noticed an uncovered temporary sewer in the courtyard.
When she peeped into it, she found Amit lying unconscious, said boy's father Harbaksh Morya, who works as a migrant labour.
The infant was immediately rushed to a nearby hospital, where he was declared brought dead. The police are yet to register a case in this regard.
Sources said the cover of the sewer was stolen a few days ago.