French consumers group UFC Que Choisir published a report on Thursday that revealed 2.8 million French people were drinking polluted tap water.
The report came with an interactive map, which showed that while 96 percent of those in France can rest assured that their tap water is fine (particularly so in big cities), it's not the same story for everyone.
The interactive map allows users to search for their town, then get information on their water quality ranging from good to very bad (see example below).
The most affected areas are in areas of intense agriculture in rural France, where pesticides and nitrates have got into the water supplies.
The south west and north central regions of France were especially bad, both areas with a lot of agriculture (see map in embedded tweet below).
Nitrates were found in the water systems of around 200,000 consumers, particularly in Loiret, Seine-et-Marne, Yonne, Aube, Marne, Pas-de-Calais and Somme.
Around three percent of households have polluted tap water due to the presence of lead, copper, or nickel from corroded pipes, the report found.
UFC Que Choisir pointed out that drinking tap water was 65 times cheaper than buying bottled water in France, and urged the government to consider "a fundamental reform of the agricultural water policy".
It also urged the government to launch an investigation into the nation's water lines, and to help anyone that might be affected by aged and corroded pipes.
The group's president Alain Bazot said that one in five people in France don't trust their tap water, and one in two prefers bottled water.