The Ministry of Health has said there should be no health concerns for Bulls residents given the very low levels found in the water, and no reason for residents not to continue using it.
PFAS chemicals are known to travel some distance in groundwater, and Mr McNeil said investigations were under way to determine the likely source of those chemicals in the groundwater in Bulls.
The Bulls water supply is being retested, as NZDF has done with all its testing for PFAS. Samples were collected last week and results are expected in about a month.
Sanson's water supply has been tested and was free of PFAS.
PFAS are a class of man-made chemicals widely used since the 1950s for products including firefighting foams used at airports and other fire training sites.
Most people are exposed to very small traces of PFAS throughout their lives, because it is used in everyday items, especially things with oil and water resistant coatings. There is no evidence that low levels of exposure cause harmful health effects.
For more information about PFAS, visit www.mfe.govt.nz/pfas