PFAS in drinking water: is it the membranes?

A study published in June has raised the question of whether the membranes that filter our drinking water could themselves be adding PFAS. It is a fair question, so I've tried to weigh the evidence honestly.

Where PFAS in drinking water mostly comes from

The Australian Drinking Water Guidelines PFAS fact sheet is clear on this. Historical use of firefighting foam has left PFAS at airports, firefighting training facilities and federal government sites. PFAS have also been found in groundwater, surface water, sewage effluent and landfill leachate. They reach drinking water sources through contaminated runoff and groundwater, and the main factor is whether a catchment or water infrastructure sits near a contaminating activity. NHMRC also says that most water supplies are already below the new, lower guideline values.

In June 2025 NHMRC updated the guideline values: PFOS 8 ng/L, PFOA 200 ng/L, PFHxS 30 ng/L and PFBS 1000 ng/L.

What the new study shows

Jiang et al. (2026), in Environmental Science & Technology Letters, tested commercial ultrafiltration membranes made of PVDF, a fluoropolymer whose use in drinking water plants the authors describe as increasing rapidly. They found:

• PFAS in new membranes, mostly PFOA (82 to 97% of the total).
• Cleaning with caustic and chlorine aged the membranes and kept releasing PFAS, up to 104 ng/L in the lab.
• Up to 371 ng/L of PFAS in chemical cleaning wastewater at a full-scale drinking water plant.

What it does not show

The study measured cleaning wastewater, not the treated water that reaches customers. The 371 ng/L figure is total PFAS in a waste stream, so it cannot be compared directly with the guideline values, which apply to individual compounds in drinking water. The study does not tell us how much, if any, ends up in the tap.

The open questions

• Treated water. I have not found any published Australian data on PFAS in the treated water from PVDF membrane plants.
• Relative contribution. I have not seen any estimate of how much membranes add compared with what already arrives in the source water.
• Disposal. Spent modules and cleaning wastewater have to go somewhere. Under the Industrial Chemicals Environmental Management Standard, PFOA is a listed chemical and waste containing listed PFAS carries disposal requirements. How that applies to used membranes has not been tested.

My conclusion

On the evidence so far, membranes are probably not the main source of PFAS in Australian drinking water. The evidence points to contaminated catchments and groundwater. But membranes are a possible contributor, it is one we could avoid, and it is one we can measure. Sampling cleaning wastewater, and treated water before and after cleans, would answer the question for a given plant. It is better to know than to assume.

I work with Micro Utilities, which offers membrane sampling and options studies. I've written a short article there on why you should be more discerning when replacing your water treatment plant membranes.

https://microutilities.com.au/insights/pvdf-membranes-pfas