Neglect by medical staff led to a man dying of dehydration in a hospital bed, a coroner has ruled.
Staff at St George's Hospital in Tooting, south London, did not give Kane Gorny vital medication to help him retain fluids during his stay in May 2009.
The 22-year-old even phoned 999 from his hospital bed as he was so desperate for a glass of water, the inquest heard.
A post-mortem examination revealed high sodium levels caused by dehydration had caused his death.
Recording a narrative verdict at Westminster Coroners' Court, deputy coroner Dr Shirley Radcliffe said Mr Gorny had died from dehydration contributed to by neglect.
– Deputy coroner Dr Shirley Radcliffe
"A cascade of individual failures has lead to an incredibly tragic outcome".
"Kane was undoubtedly let down by incompetence of staff, poor communication, lack of leadership, both medical and nursing, a culture of assumption."
ITV News' Paul Davies reports.
Mr Gorny was suffering from diabetes insipidus, a condition which caused him to be aggressive towards nurses on May 27 2009, the day before he died.
He had been sedated and put in a side room following his outburst.
The inquest heard medical staff were "blinkered" by his previous behavioural problems after he complained of feeling thirsty.
Dr Radcliffe said staff nurse Sharon Gibbs, who was caring for Mr Gorny during his violent outbursts on May 27, was "out of her depth" and should have had senior help.
Speaking outside the court, the lawyer for Mr Gorny's family, James Stevenson, said they were "devastated by the number of missed opportunities" to prevent his death.
He also said: "There were systemic and individual failures in the level of care provided to Kane."
Dr Ros Given-Wilson, medical director at St George's Healthcare NHS Trust, said "We deeply regret the death of Kane Gorny".
– Dr Ros Given-Wilson, medical director at St George's Healthcare NHS Trust
It is clear that the care we provided on this occasion fell short of expectation in a number of respects and for this we are profoundly sorry.
We have admitted civil liability for the failures in Kane's care and we fully accept the coroner's verdict.
Since Kane died in 2009, we have made changes to senior leadership on our wards and put a number of patient safety measures in place."
A Department of Health spokeswoman said: "This is a very tragic case. Every patient expects to receive safe and high quality care, and to be treated with compassion.
"There is no excuse for any hospital to be providing poor quality services for patients.
"All hospitals need to ensure they are focusing on what matters to patients and getting the simple things, as well as the clinically technical decisions, right."