Anthony Williams-Daly, who was sharing a bath with two of his siblings, slipped under the water and drowned when his mother left the bathroom briefly to fetch a towel.
It is understood his mother returned within seconds.
The incident happened at about 9pm on Monday night and emergency services were summoned to the home at Birchwood Close, Onslow Gardens, outside Blackpool, Cork.
Attempts by paramedics to revive the child were unsuccessful.
A Garda escort accompanied the ambulance to the Mercy University Hospital, where further attempts to resuscitate the infant failed.
Baby Anthony was pronounced dead at 10.30pm.
A postmortem, conducted yesterday at the hospital, ruled out any foul play.
Superintendent Con Cadogan, who is based at Gurranabraher Garda Station, described the child’s death as “a shocking tragedy”.
“The circumstances behind the death proved to be extremely difficult to handle for ambulance crew and gardaí, many of whom are parents themselves.
“Words can’t describe what the family themselves must be going through.”
The superintendent, who is leading the investigation into the infant’s death, said gardaí extended their deepest sympathy to the family at a very difficult time.
He said he understood that the HSE is offering counselling services to the family.
The Bishop of Cork and Ross, Dr John Buckley, said a terrible tragedy had befallen the family.
“My thoughts and prayers are with the Williams-Daly family at this time.”
Gardaí are preparing a file for the coroner’s court, as is required in such circumstances.
Baby Anthony is survived by his heartbroken parents, Maryann and Frederick, and by his brother James and two sisters, Bridget and Brittany.
Separately, a married couple in their 30s were in a critical condition last night after the car in which they were travelling ended up under a heavily loaded trailer a couple of miles outside Cork city.
The accident occurred when their car, a reddish-coloured Suzuki with an 02-C number plate, collided with a tractor and trailer at Killydonoghue, Glanmire, on the old N8 at around 3.40pm yesterday.
The two occupants of the car, from the Donaghmore area, were taken by ambulance to Cork University Hospital (CUH).
A Garda spokesperson said they were in a critical condition. The road was closed off for a time and diversions put in place to allow forensic crash investigators examine the scene.