Campylobacter symptoms spread through the retirement village, schools and businesses in Havelock North.
At least four deaths have now been attributed to the outbreak which affected more than 5000 people, put 44 in hospital and led to a major Government-ordered public inquiry.
Keith Sparksman agrees with the coroner's view that his mother, who had been otherwise healthy until she became ill, lived 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, and did not seek medical help because of that.
He said his mother, born and bred in Hastings, was "independent", having only a short while previously sold her home and moved to the lifecare centre. She'd lived in Hastings as a widow for 15 years after the passing of her husband, and had only recently stopped driving after more than 50 years with a licence.
Keith Sparksman said his mother probably had a right to assume she would be looked after.
His sister has been reported as a saying the complex was in lockdown in the belief there had been a norovirus outbreak, and it may have been different had staff been aware of the water contamination.
A caregiver had visited Jean Sparksman after she was reported by another resident to be unwell three days before her death.
Because of her symptoms she was given a glass of rehydration fluid and encouraged to maintain a high fluid intake.
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 did not blame staff, saying that while a GP believed Jean Sparksman should been seen by a health professional on August 12, when she was not improving, she "managed all aspects of her own health" and there was no responsibility on the caregivers to refer her to primary health care.