Hunter Water says the Lower Hunter's drinking water supplies already meet proposed new guidelines for per-and poly-fluoroalkyl (PFAS) substances.
The National Health and Medical Research Council proposed on Monday to reduce the amount of the potential cancer-causing chemicals allowed in Australian drinking water.
However, they will not be reduced to the near-zero levels set by the US Environment Protection Authority.
PFAS substances are a group of more than 15,000 chemicals resistant to heat, stains, grease and water, earning the nickname "forever chemicals" due to their inability to break down.
Their use has varied widely from firefighting foam to non-stick pots and pans.
Recent discoveries of elevated quantities of the chemicals in some NSW water supplies have led to dam closures and community concern, particularly in the Blue Mountains.
Hunter Water has been monitoring the Lower Hunter's water supply for PFAS for the past eight years.
"A review of our historical water quality monitoring data for the region's distribution network indicates that our drinking water complies with the proposed new PFAS guidelines and is safe to drink, whether we use the current or proposed future PFAS guidelines," a spokesman said.
"Hunter Water is committed - as we are always - to supplying high-quality safe drinking water that complies with the Australian Drinking Water Guidelines (ADWG)."
Water quality expert Stuart Khan said Australians could remain confident the national guidelines incorporated the latest and most robust science to underpin drinking water safety.
But he warned upgrades to treatment plants to meet the lower standards would come at a cost to consumers.
"In some cases, advanced water treatment processes may be needed and the cost of these advances will necessarily flow through to customer bills," the head of the University of Sydney School of Civil Engineering said.
"Drinking water cost increases will hit smaller regional communities hardest."
The PFAS guidelines are based on animal studies due to a lack of high-quality human studies.
Water Services Association of Australia executive director Adam Lovell said the sector supported the thorough scientific process used to set the guidelines.
"For most of us, drinking water is sourced from well-protected, often pristine catchments, or it goes through multiple barrier treatment processes," he said.
The guidelines, if adopted, would reduce the benchmark for the PFOA group of chemicals from 560 to 200 nanograms per litre based on cancer-causing effects.
One nanogram is about one drop in 20 Olympic-sized swimming pools.
PFOS guidelines would fall from 70 to four nanograms per litre based on effects on bone marrow, while new guidelines were set for the PFHxS and PFBS groups over thyroid concerns.
Each level was based on lifetime exposure risks, the research council said.
"It's not about the concentration that is toxic right now but you need to be drinking above these levels for your entire life to have what we regard at the moment, as toxic effects," the council's chief executive, Steve Wesselingh, said.
The new guidelines were based on animal studies after the council's water-quality advisory committee took the view there were no sufficient, high-quality human studies available.
Placing more weight on those human studies and legal differences led the US Environmental Protection Agency in April to adopt near-zero standards, advisory committee member David Cunliffe said.
"Our guidelines are very conservative," he said.
"We always err on the side of caution."
