PFAS in Drinking Water: Why a Home Water Filter Is Not the Solution

The most common technologies used in household water filters are activated carbon filtration and reverse osmosis. “Drinking water companies use activated carbon in filters that are about five metres high,” Hofman explains. “Household filters, by contrast, contain filter beds of only 10 to 20 centimetres. In addition, PFAS are known to be difficult to remove using activated carbon. Small PFAS compounds, such as trifluoroacetic acid (TFA), are hardly adsorbed at all. Larger PFAS compounds may initially be captured, but only for a limited period. While these filters still can remove other organic micropollutants, like pharmaceuticals, they will have to be reactivated because they don’t remove PFAS anymore.”

This is why drinking water companies replace their activated carbon more frequently. “A consumer filter may remove some PFAS at first, but it quickly becomes saturated and loses its effectiveness, just like the large scale filters,” says Hofman. “The filter’s expected lifespan and replacement recommendations are based on their effectiveness for the removal of other micropollutants, but for PFAS this is not sufficient.” By the way, the organic micropollutants the filters have been designed for, are not present in Dutch tapwater. The loaded activated carbon is disposed of as regular waste, but regular waste-processing installations cannot destroy PFAS, and will discharge them into the environment. Activated carbon filters from drinking water utilities are sent to a specialised waste treatment company, where PFAS are effectively broken down.

Reverse osmosis

In addition to activated carbon, reverse osmosis can remove smaller PFAS compounds.“With reverse osmosis, virtually everything is removed from the water,” Roberta explains. “As a result, the water no longer contains essential minerals and therefore does not meet the legal quality requirements for drinking water. Drinking demineralised water is not healthy unless those minerals are replenished in another way.” Reverse osmosis systems also have other drawbacks. For every 3 litres of purified water produced, approximately 7 litres of water are discharged. In addition, the process generates wastewater. A further concern is maintenance. If filters are not properly maintained, bacteria can grow inside them, leading to deterioration of the microbiological quality of the water. Hofman has previously highlighted this issue in national media.

Professional article on PFAS removal and degradation

In a recent article published in the Dutch water sector journal H₂O, Hofman and fellow researchers describe how the further removal and degradation of PFAS during drinking water production remains a complex challenge. Although treatment technologies are available and continue to advance, they pose challenges related to effectiveness, residual waste streams, energy consumption, and sustainability. The most effective solution therefore remains preventing further PFAS emissions at the source. At the same time, KWR continues to investigate how PFAS can be removed and degraded more effectively and sustainably, thereby contributing to safe, future-proof drinking water supplies.