A family is demanding answers after a blind, 80-year-old man with dementia fell into a canal after being discharged from hospital.
Manchester Royal Infirmary staff placed Neville Tyldesley alone in a taxi, which was given the wrong home address.
The Manchester Evening News reported he became confused and stumbled into a canal.
Central Manchester University Hospitals NHS Foundation Trust has apologised and expressed its "sincere regret".
Mr Tyldesley, who was still wearing a pyjama top and had a cannula tube in his arm, was rescued from the water by a passing jogger.
His daughter Beverley Stringer learned of his accident when she received a phone call as she went to collect him from hospital.
"I literally screamed the hospital down," she said.
Ms Stringer said she was told by a nurse on the ward her father had been sent home in a taxi, but to an address she realised was his former home in Miles Platting, Manchester.
His other daughter Diane Brannan said her father was in a "shocking state" when the jogger brought him to her house.
She added: "He was freezing to death... he was shaking that much he couldn't sit down on the sofa."
Ms Brannan said her father would have died if the jogger had not spotted him.
"It doesn't bear thinking about. We want a lot of answers," she said.
Ms Stringer added: "It is unbelievable, it should never have happened."
In a statement, the Trust said: "Our patients' safety is our utmost priority and Mr Tyldesley was assessed by a member of our team before his discharge.
"We have launched a full investigation into how this decision was reached."