A terminally ill patient who died at a Perth hospital had contracted Legionnaires' disease after deadly bacteria was found in the facility's water supply.
Officials have confirmed a post-mortem of the patient at Sir Charles Gairdner Hospital returned a positive result for Legionella pneumophila.
The North Metropolitan Health Service said the person had been receiving palliative care and it could not be certain what caused their death.
"It cannot be concluded that the patient passed away as a direct result of Legionella pneumophila," an official said.
"The hospital does not receive the coroner's autopsy report so it is not possible to determine the contribution of the Legionella."
The hospital became aware of the infection last month and subsequently closed two rooms on a cancer ward so water sampling could be undertaken and filters installed.
"These initial samples returned a positive result for Legionella pneumophila, and remediation including heated water flushing commenced," the official said.
One room was declared safe and reopened but the other remains closed for further testing.
Filters were installed in a further 14 rooms which also underwent heated water flushing.
The official said a review of all inpatients who recently stayed in the rooms had found no other infections.
The risk to staff and patients was considered "extremely low" but two high-risk patients on the same ward were put on prophylactic antibiotics as a precaution.
"Patients are notified if there is a disruption to their usual care in the hospital. If there was an ongoing safety risk from the water they would also have been notified," the official said.
"This was not the case as the water safety was mitigated by the immediate instillation of bacterial filters.
"It is not uncommon for some bacteria to be found in a hospital's water supply."
Health Minister Roger Cook was asked in parliament last week about reports of bacterial contamination at SCGH and replied he had "received no brief to the effect that there is any concern with the hospital water".
In a statement, the minister expressed frustration he had not been alerted to the problem by department officials.
"I am disappointed that I was not informed of the issue until after it was raised in parliament. I have written to the chair of the North Metropolitan Health Board to this effect," Mr Cook said.
"It is essential that significant matters such as these are identified and brought to my attention."
Mr Cook said the government would pursue legislative change to ensure post-mortem results could be provided to treating clinicians and hospitals.
Opposition health spokeswoman Libby Mettam said it was extraordinary the health minister had been in the dark about the contamination issue for more than a month.
"To have the water supply at risk at one of our major tertiary hospitals also shows a lack of forward planning and investment in our ageing health infrastructure and highlights the McGowan government's inability to manage our health system," she said.
Australian Associated Press