She then worked on another area and forgot to put the bottle back in the cleaning cupboard.
Another staff member put the bottle in the refrigerator with the other soft drinks.
It was later served to Mrs Murphy.
Chemicals used in unmarked plastic bottles, with no warnings or instructions was common throughout the industry and it was "only a matter of time before something like this occurred'' again, said Crest Clean managing director Grant McLauchlan.
"This needs to change.
"The Department of Labour is responsible for enforcing health and safety and preventing or managing the adverse effects of hazardous substances.
"Crest strongly believes that better standards of training are urgently needed as this incident at the Avondale RSA proves,'' said Mr McLauchlan.''
He said the Department needed to set a minimum standard of training, and require cleaners to at least undertake a NZQA course in cleaning and caretaking.''