A coroner has confirmed Havelock North's water contamination resulted in the death of pensioner Jean Sparksman.
She was found dead at a Mary Doyle Lifecare Complex apartment in Havelock North on August 13, 2016. She was 89.
Coroner Peter Ryan says in his report he is satisfied that she died "as a result of becoming infected with campylobacter in a background of coronary artery disease and appendiceal tumour".
But the artery condition had not been discovered at the time she had been taken ill a few days before her passing, and the coroner says she did not seek medical attention, possibly with a "false sense of security" generated by the serviced-apartment and monitored environment in which she lived a short distance from the Havelock North village centre.
"Although she was monitored by caregivers on a regular basis, these people were not qualified nor expected to assess the extent of her illness," he said.
"The caregivers did encourage Mrs Sparksman to maintain a high fluid intake and continued to monitor her vital signs," he said.
He said she had not shown symptoms of heart disease before another resident reported to a caregiver on August 10, 2016, that Sparksman was unwell.
Vital signs were considered within normal range but because of the symptoms the team leader gave her a glass of rehydration fluid and encouraged her to maintain a high fluid intake.
It was the day before the outbreak of gastroenteritis was detected among residents of the complex, leading to the widespread alert as symptoms spread through schools and workplaces and affected thousands of people in the community.
Further visits took place. There were "no other obvious" concerns when she was visited about 2am on August 13, but she was found dead in the apartment about 5.45am.
The coroner said a pathologist considered the death resulted from an interaction between pre-existing natural diseases and an infective gastroenteritis.
"The pre-existing natural diseases have made her more susceptible to the effects of the gastroenteritis," Ryan said.
A GP believed Sparksman should been seen by a health professional on August 12, but as she "managed all aspects of her own health" there was no responsibility on the caregivers to refer her to primary health care.