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The pair became ill after they drank what they thought was water from a jug on the bar at the RSA, only to find the liquid was probably the chemical solution.
A third person, a 61-year-old man, who did not consume as much of the liquid as the others, was released from hospital on Saturday.
All three were members of the Waikouaiti RSA, Detective Sergeant Chris Henderson, of Dunedin, said.
A sample of the liquid was sent to ESR for analysis, but police inquiries suggested the liquid was possibly a chemical cleaner used to clean beer lines, he said.
The active ingredients in beer-line cleaners are generally heavy-duty alkaline chemicals with corrosive qualities similar to those used in drain cleaners.
Dunedin RSA president Jenepher Glover said she had visited the two in hospital and they were "quite bright and quite philosophical" about the incident.
They had suffered burns to their oesophagi down to their stomachs, but it was hoped both would make a full recovery.
It was an awful time both for the pair - who would now miss the Anzac Day commemorations - and for the whole community, she said.
The incident was unfortunate, and seemed like one of those things that "just happened".
"It could have been a lot worse, but thank God it's not."
Waikouaiti RSA did not take ODT calls yesterday.
The Department of Labour is investigating the incident.