The elderly man had attended a function at the Sentinel's spa area in late February or early March, celebrating the building's 10 year anniversary and the departure of the manager and his wife. He is not believed to have entered the spa itself.
By March 19, he was admitted to North Shore Hospital. Legionnaires was discovered in his system three days later and he died on March 27.
Building manager Warren Doel told the Herald he took over management of the complex on March 5.
He said he didn't attend the anniversary event which the man and his wife had attended.
When asked how legionnaires was found in the spa by authorities in late March, Doel said it was in the middle of the spa's quarterly maintenance period so it was closed, turned off and the pumps were not operating.
As for the day the man could possibly have contracted the disease, Doel said he had seen photos of the spa on the day and its cover was on. He doubted any contagious steam would have seeped out.
"Nothing's impossible but it's highly unlikely."
He said he didn't inform the building's residents as he didn't want to be "sensationalist" and "it wasn't a secret or anything".
"Sometimes when you say things like that you are unduly alarming them about something that's not really an issue, that's what I thought anyway. I can tell them that it's happened but it's only an interesting fact, I didn't see that there was a danger there.
"It's six or seven weeks after the event."
The pool was always chlorinated, cleaned every week and shut down quarterly for maintenance, he added.
Dr Jay Harrower, Public Health Medicine Specialist at the Auckland Regional Public Health Service (ARPHS), said it was notified by North Shore Hospital of a man who had contracted legionnaires on March 22.
"ARPHS interviewed the man and his family to discover where he may have been exposed to the bacteria. Staff also took water samples from the man's apartment, spa, swimming pool and the cooling tower in the apartment complex.
"The spa tested positive for legionella bacteria and ARPHS requested the building manager undertake immediate remediation."
That included "super-chlorination" of not only the spa pool but also the adjacent swimming pool.
"There have been no other cases notified from this apartment building."
Harrower said the building owner responded quickly to help deal with the "possible source of contamination".
"If there had been any delay in treating the spa, then the service would have required the building owner to alert residents of the risk. ARPHS investigated the case, established a possible source and ensured that the required remediation took place."
The type of Legionnaires' disease identified in the man's case was commonly associated with man-made warm water systems, he said.
"It is usually contracted directly by inhaling water droplets from a contaminated source. The disease is not caught from drinking water, nor can it be passed from person to person.
"Older people are more susceptible to catching Legionnaires' disease as they often have reduced immunity and they are more likely to develop pneumonia. People can become very sick and require hospital treatment, often in intensive care."
Sentinel resident Amanda Care was furious at not being told legionella had been found in the pool.
She had lived at the complex for two years and regularly used the spa. She felt management should have shared the information with apartment owners and renters.
Other residents spoken to were also concerned at not being told as they had also been using the spa around that time.
When contacted, Auckland Council and the Ministry of Health said they did not need to get involved, while Worksafe said it had not been alerted.
A spokeswoman for the Ministry of Business, Innovation and Employment said there was no relevant offence committed under the Building Act.
The coroner's office confirmed it is not investigating the man's death.
The Sentinel's body corporate manager said she was unable to comment.
LEGIONNAIRES DISEASE
• 49 cases of legionnaires disease reported in Auckland in 2017,
• 23 were soil/potting mix related, 18 were water borne, the rest were 'other'.
• 6 of the 49 died
• Elderly men with low immune systems most susceptible to legionnaires
• The incubation period for the disease is 14 days
• To keep your spa free of legionella, follow manufacturer's instructions for regular cleaning
• Vary the biocide – cleaning product – every few years as pooling system acclimatizes to similar product
SOURCE: John Whitmore, ARPHS environmental health advisor