Bottled water or tap water, which one to trust?

Bottled water, tap water, a new survey from the magazine “60 Millions de consommateurs” this month. The French buy 8 billion bottles of water per year. Decryption with Patricia Chairopoulos,

Two months ago, franceinfo revealed the conclusions of an ANSES report on the health quality of water from the NESTLE group. The experts noted an insufficient level of confidence, due to regular microbiological contaminations, and the use of illicit purification treatments. Can we still trust bottled water?

Journalist Patricia Chairopoulos, this month in 60 million consumers, devotes a long article on the quality of the water we drink every day.

franceinfo: Can we really say that bottled water is less polluted than tap water?

Patricia Chairopoulos: Not necessarily ! A report from the National Agency for Food, Environmental and Occupational Health Safety (ANSES), submitted to the Ministry of Health in mid-2023, highlighted the non-compliance with the water quality of the Nestlé Waters group (Perrier, Contrex, Vittel, Hépar…). The cause: regular microbiological contamination (coliform bacteria, Escherichia colienterococci) on many wells, the presence of per and polyfluoroalkyl (PFAS), or even pesticide residues.

Does this mean that the mineral water or spring water we buy is not necessarily natural? That she is sometimes treated too?

We can say so, at least for certain brands. Another report, this time from the General Inspectorate of Social Affairs, showed that around 30% of bottled water brands underwent strictly prohibited purification treatments, such as activated carbon filters.

What about tap water? It is sometimes said that its qualities are better than bottled water?

In fact, it is very controlled. But it is also more exposed to various contaminations linked to industrial and agricultural activities, near catchment areas. This is why the Regional Health Agencies ensure a multitude of criteria; for example, there are 200 to 300 pesticides and metabolites that must be searched for, to which other pollutants may be added, depending on local agricultural activities, the quantities of pesticides sold, etc.

What are the most frequent and most dangerous contaminations for health?

In tap water, we rarely deal with bacteriological contamination, since the water is chlorinated before its distribution in the network. The major problem is mainly due to contaminants that we do not yet know, and therefore are not sought after.

This is the case of degradation products of certain pesticides, the dangerousness of which is unknown, or of eternal pollutants, that is to say perfluorinated substances. In certain places, notably in the Auvergne-Rhône-Alpes region, we exceeded the threshold of normality (0.1 microgram/liter) for the sum of 20 PFAS retained by Europe, for their high probability of being found in the water, and accumulate in organisms.

But who is the supervisory authority? How’s it going ?

It is the Regional Health Agencies which manage the lists of molecules to be searched for, and each operator is required to carry out regular checks. For their part, the agencies take one-off samples, and in particular, from areas deemed to be at risk, for example with high industrial activity.

But when water is contaminated, does it really become drinkable again after treatment?

Already, water can be classified as “non-compliant” for a few days, following a regulatory threshold being exceeded, but not undrinkable, in the health sense. That being said, the stations are equipped with complex filtration systems, based on activated carbon or reverse osmosis, effective in retaining conventional pesticides… But not always micropollutants such as smaller metabolites. Large producers have the means to equip themselves with more efficient systems, such as nano membrane treatment.

But these treatments are expensive… Are all production plants the same? In rural areas for example, do the structures exist?

And no. In rural areas, financial resources are often lower, and there is a risk that the quality of tap water will be at two levels.

Last thing, we are talking more and more about the means available at home to filter tap water and improve its quality, filter jugs for example, are they reliable?

Yes, to retain chlorine, and therefore remove the sometimes unpleasant taste of tap water, as well as a small part of the ions responsible for the formation of limescale and also certain metals such as lead. But no recent study has made it possible to evaluate their effectiveness for pollutants such as pesticides, drug residues, perfluorochemicals, etc.