Since the beginning of this year, testing for 20 PFAS – or "forever chemicals" – has become mandatory in France under a European directive. But detecting and removing micro-pollutants from water is a challenge, and consumers could end up footing the bill.
At a pilot plant run by the Île-de-France Water Authority (Sedif), water is stripped of pesticides, forever chemicals and other pharmaceutical residues.
This is done using "membranes", reveals Camille Pain-Le-Quere, an engineer for Franciliane, the company appointed by Sedif to manage its drinking water. She is responsible for monitoring the pilot facility.
"A membrane is a filtering material which, under pressure, retains certain compounds in the water. These are spiral-wound membranes. The water goes in and the clean water comes out in the centre," she explains.
"These membranes combine nanofiltration and reverse osmosis. And with nanofiltration, we’re talking about 1/1000 of a micron. So, any molecules larger than 10⁻⁹ metres are retained."
Behind the pipes, taps allow both the clean water and the water containing all the filtered pollutants to be collected. In the absence of a large-scale solution, the latter will be returned to the Seine.
This plant would reduce the quantity of the 20 PFAS, for which detection is now mandatory in drinking water, by 90 percent.
EU tightens rules on 'forever chemicals' in drinking water
However, Thomas Martin, head of feasibility studies at Sedif, cannot say precisely how much of these substances remain.
"We are at the detection limits of laboratory analytical equipment," he says. "It is difficult today to quantify the parts per million in litres of drinking water being distributed."
In any case, this process would filter out pollutants well beyond those listed in the regulations.
"The membranes block what we know about today, but they also block what we don’t know about," explains Guillaume de Stordeur, Sedif’s communications manager.
The investment required is considerable – and will be passed on to the consumer, he added.
"The total investment amounts to around €1 billion, which must be set against the 4 million users. This investment cost will be passed on to the drinking water consumer’s final bill."
'Forever chemicals' could cost Europe €1.7 trillion by 2050
Depending on the region, the impact on consumers could be more or less significant, warns the UFC-Que Choisir consumer watchdog.
According to Olivier Andrault, a policy officer at the organisation, removing pesticides and nitrates would require at least €1 billion a year.
"It is to protest against this injustice that UFC-Que Choisir has sent consumers a fake €1 billion bill, to be returned to the decision-makers," he said. "They have the power to decide to protect our drinking water sources with measures banning the use of pesticides near the most sensitive water sources."
UFC-Que Choisir also would like to see an increase in the tax on pesticide use.
As for PFAS, a levy is being introduced for manufacturers who discharge them into water.
This article was adapted from the original version in French by Pauline Gleize.
