People in a Victorian town are being given bottled water and told to drink only that, while an investigation into possible groundwater contamination gets under way.
There are concerns elevated levels of the fire-fighting chemical PFOS detected at a training facility outside Penshurst may have contaminated bores and other local water sources.
About 700 residents are being provided with bottled water for now.
The potential Penshurst contamination was detected as part of state-wide testing of CFA facilities triggered by contamination at a similar training centre at Fiskville, which is now closed and the subject of an inquiry.
The statewide testing found PFOS levels in groundwater and soil at several training sites that exceeded international standards, although this posed a possible risk to the public only at Penshurst.
"We don't want to take any risks in relation to this as the whole town does rely on groundwater," Environment Minister Lisa Neville said.
"I would stress that we are being very, very cautionary here and all advice is there is a very low risk in relation to the drinking water of this town."
Penshurst's water authority started testing the drinking water on Thursday and results are expected in about a week.
Precautionary drink water testing will also occur for Wangaratta, Bangholme and Longerenong after elevated PFOS levels were also detected at their CFA facilities, though the contamination is considered contained to each site.
The United Firefighters Union has again called for the CFA board to be sacked.
"The CFA has learnt nothing from the cancer cluster at Fiskville," union secretary Peter Marshall said.
PFOS has been banned for use in fire-fighting chemicals since 2007.