An investigation by the NSW Environment Protection Authority (EPA) has found the former National Textiles site, now owned by Cleanaway, as potentially responsible for per- and poly-fluoroalkyl [PFAS] chemicals ending up in waterways that run to the Hunter River.

According to the EPA, the pollution is historic and not linked to the Cleanaway operations at the Kyle St site. National Textiles, formerly Bradmill, was one of the biggest employers in Maitland when it collapsed in January 2000.

Another Kyle St business, Truegain - also known as Australian Waste Oil Refineries - was forced into liquidation in September 2016, seven months after it was caught discharging PFAS chemicals, up to nearly 400 times the accepted health risk limit, into the sewer.

The company's atrocious environmental record, exposed by a Newcastle Herald investigation, included oil and liquid waste dumping into surrounding waterways and properties dating back decades.

Investigations revealed PFAS up to 10,000 times the accepted health risk level, in multiple storage tanks at the Rutherford refinery. A major cleanup operation is ongoing to treat more than 3 million litres of contaminated PFAS water.

The EPA continued its search for other possible sources of PFAS contamination in the area, after levels more than 50 times the safe drinking water guidelines were found upstream of the former Truegain site.

A spokesman told the Herald this week that sampling between the New England Highway and Wollombi Rd had identified the former National Textiles site.

He said Cleanaway had "inherited" the pollution problem and was "voluntarily undertaking an investigation to establish the extent of any PFAS contamination sources".

The environmental watchdog's publicly issued data shows concentrations of the contaminant as high as 4.08 micrograms per litre were found in a stormwater drain about 200m from the former Truegain site in June - 58 times the safe drinking water level and 5.8 times higher than the recommended safe level for recreational use.

The data shows the reading was lower the previous month - 2.81 micrograms per litre - and dropped slightly between the June and July testing to 3.67 micrograms per litre. Further testing was conducted in February that identified the former National Textiles site as the potential source.

Soil and groundwater pollution testing has been carried out at the Truegain site and the results are being analysed. The EPA has previously vowed to keep the public informed about the testing.

An EPA warning to residents not to eat eggs, drink milk or consume meat from animals that have had access to Fishery or Wallis creeks remains in place after PFAS chemicals, above the recommended drinking water guideline, were found in Stony Creek that runs behind the Truegain site.