Counties Manukau District Health Board has linked raw sewage leaking out of pipes to a bad bacteria outbreak at Middlemore Hospital in 2014.
Acting chief executive Gloria Johnson admitted to RNZ this week that sewage from deteriorating pipes has been leaking into walls at the hospital's Scott building, which houses the main reception, cafeteria, coronary care and 11 wards.
She said other hospital buildings with the same pipes probably also had sewage leakages.
The DHB has now told RNZ the sewage leak was made public on 2 November, 2014, in an NZ Herald report that detailed an outbreak of contagious and potentially fatal bacteria, vancomycin-resistant enterococcus (VRE) at its dialysis unit.
The Herald reported an Infection Prevention and Control analysis had identified a lack of toilets and a leaking sewer pipe as factors making the dialysis unit "unfit for current purpose".
However, the DHB at the time said the leaking sewage did not relate directly to the bug outbreak.
RNZ requested the Infection Prevention and Control report, as well as details of what the DHB had done to fix the problem, especially in light of Dr Johnson saying other buildings' sewerage may also be leaking.
Outbreaks of norovirus also occurred at Middlemore in February 2014 and October 2012.
RNZ asked the DHB if it knew whether these were linked to leaking sewage.
Middlemore Hospital serves half a million people a year.