Judith "Judy" Ann Ingham was 89 when she stepped into a 70C bath at her apartment on Sydney's lower north shore in August 2022.
A neighbour who was called over removed the plug from the bath using a spatula so he did not burn his hands.
Ms Ingham was rushed to hospital with burns on her armpit and back covering 16 per cent of her body.
She died 26 days later.
The pharmacist, who had received an Order of Australia medal for contributions to the healthcare sector, left behind 16 grandchildren and 10 great grandchildren.
In February, coroner Rebecca Hosking presided over an inquest into Ms Ingham's death where she was asked to refer the 89-year-old's plumber to SafeWork NSW.
Handing down her findings on Tuesday, she agreed by recommending the safety watchdog investigate Michael King, operational manager of Hillier Plumbing.
Mr King allegedly failed to install a temperature control device in the hot water system when he replaced it in April 2022 and did not notify SafeWork NSW after Ms Ingham's death.
By law, apartment block hot water systems are meant to keep water above 60C to prevent bacterial build-up.
Temperature control devices mix this hot water with cold, ensuring that what flows out of taps within a home does not exceed 50C.
During an inspection after Ms Ingham was burnt, a Hillier Plumbing employee found the water temperature in the building reached a maximum of 73C.
In September 2022, another plumbing company was retained to install temperature control devices in the building.
Ms Hosking on Tuesday also recommended that the Building Commission NSW offer improved education to plumbers and require compliance certification for work on hot water systems.
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