The Environmental Protection Authority says it is not aware of any firefighting foams containing banned chemicals that are still being used anywhere in the country.
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This follows tests showing groundwater at five sites in Taranaki is contaminated with PFOS chemical at above safe levels.
The oil company Shell is now removing its stocks of PFOS foam, 12 years after it was banned.
The EPA said the other foam containing the second of two banned foam chemicals, PFOA, was also not in use anymore.
"There are only a very small number of places within New Zealand where these foams can be found and we are working with them to check that their storage arrangements ensure environmental safety," Dr Fiona Thomson-Carter, general manager of Hazardous Substances and New Organisms, said.
"Provided the foams are appropriately stored, they pose no immediate risk to people or the environment.
"Our aim is to ensure facilities with these foams comply with the regulations, and the firms involved are being highly co-operative."
The EPA has declined to name the facilities that still hold banned foam, though it has been found at four small airports, and Auckland Airport has admitted it probably still has some, without saying how much.
Shell has also not answered RNZ's questions about what quantities of PFOS foam were discharged during training or emergencies, and when.
Shell said the use of the banned foam was "historical".
"Recent practice when testing these [firefighting] systems has been to drain the foam directly from the roof of the tank to containment," a Shell spokesperson said by email.
The company would not agree to an interview.
The EPA has not answered RNZ's questions about whether Shell could or should be prosecuted.