The disruption it caused was just another example of a long series of challenges now-disheartened clinicians faced, staff said.
Health New Zealand Te Whatu Ora said it was urgently working to resolve the issue - work was scheduled for 11pm last night - and a senior leader apologised to patients and staff at Dunedin Hospital.
A member of staff who anonymously supplied a photograph of the leak to the Otago Daily Times yesterday invited Prime Minister Christopher Luxon to visit the ageing facility "so he can see for himself why Dunedin so desperately needs a new hospital which is fit for purpose".
Consultant anaesthetist and clinical director of anaesthesia Dr Claire Ireland said clinical teams were "very frustrated" with their working environment and felt for patients already facing long waits for surgery.
"The leak that occurred today in the main operating theatres, resulting in a partial roof collapse into the sterile stores area, is another example of some of the challenges we face working in an end-of-life building with failing infrastructure that is not fit for purpose.
"There are many other examples, including a leak from a failed ventilation system resulting in a 2m-long crack appearing in the ceiling of an operating theatre during an operation.
"The dirty water that ran through the crack fortunately did not enter the surgical site, but to the side of the theatre bed where the surgical staff were working.
"On that occasion we had to cancel another operating list and move the patient to that operating theatre to complete their operation."
These leaks were in addition to those that happened during heavy rain, which affected theatre corridors and recovery areas.
Water came in through windows in operating theatres and at the theatre reception during those events.
"All of these scenarios add delays and inefficiency as we find solutions to continue safely with surgery," Dr Ireland said.
"Clinical teams working in this environment feel very frustrated at the lack of efficiency when patients across the southern region are already facing long waiting times to access planned care."
There was serious concern among clinical staff about the government considering retrofitting the old hospital building to keep Dunedin’s new hospital under its budget limit.
Pursuing that option would mean it would likely be another 10 years before clinicians saw replacement operating theatres - and then another several years before a refurbished ward block, she said.
HNZ Te Waipounamu regional head of infrastructure Dr Rob Ojala said the leak was caused by an issue with a fitting in a water pipeline in the floor above.
A cold-water shutdown was scheduled last night to carry out the "necessary permanent repairs".
The work was scheduled for 11pm and was expected to take three to four hours, Dr Ojala said.
A diversion was put in place to make sure the department could continue to operate in the meantime, he said.
"We are working closely with the clinical and operational teams to ensure the disruption is minimised and we can continue to deliver safe patient care," Dr Ojala said.
"We understand this situation may be upsetting for some patients and staff and we apologise for any disruption caused.
"We acknowledge Dunedin Hospital is an ageing facility and with that comes challenges with infrastructure."
Dr Ojala said HNZ continued to work urgently to present initial options analysis and advice for ministers "as soon as possible" on how to deliver "modern, fit-for-purpose health facilities to enhance clinical safety and enable new models of care, and that can be achieved within the budget outlined".
A spokeswoman from the prime minister’s office said the government was "committed to building a new hospital worth $1.88 billion".
"The prime minister has been to Dunedin twice recently and any further visits will be advised when they are imminent," she said.
In Queenstown at the weekend, Mr Luxon said the government would not budge on its budget limit for the project.
