Two infant boys have drowned in separate incidents at homes in Sydney's west.


In the first tragic incident on Thursday afternoon, an 11-month-old boy was found with his head in a bucket of water in the bathroom of his family's Fairfield home.


Police say they were told the infant had been with his siblings and mother when he wandered away about 5pm (AEST).


One of his siblings found him a short time later with his head under water.


He was taken to Westmead Children's Hospital, but died a short time later.


Meanwhile, an 18-month-old boy was found floating in a Greystanes pool about 5.30pm.


Police said his father and uncle, who were caring for the child, noticed him missing about 5.20pm.


They searched the house before finding him in the swimming pool.


He was also taken to Westmead Children's Hospital, where he died.


AAP