France's multi-billion euro mineral water companies are under the spotlight because of climate change and growing concerns about the industry's environmental impact, reports BBC News.
At issue is whether some world-famous brands, notably the iconic Perrier label, can even continue calling themselves "natural mineral water".
A decision in the Perrier case is due in the coming months. It follows revelations in the French media about illicit filtration systems that have been widely used in the industry, apparently because of worries about water contamination, after years of drought linked to climate change.
"This really is our Water-gate," says Stéphane Mandard, who has led investigations at Le Monde newspaper. "It's a combination of industrial fraud and state collusion."
"And now there is a real Sword of Damocles hanging over the head of Perrier."
According to hydrologist Emma Haziza, "the commercial model of the big producers has worked very well. But it is absolutely not sustainable at a time of global climate change".
"When you have big brands that feel they have no choice but to treat their water – that means they know there is a problem with the quality."
The story hit the headlines a year ago in France after an investigation by Le Monde and Radio France revealed that at least a third of mineral water sold in France had been illegally treated, either with ultra-violet light, carbon filters or ultra-fine micro-meshes commonly used to screen out bacteria.
The issue was not one of public health. The treated water was by definition safe to drink.
The problem was that under EU law, "natural mineral water" – which sells at a huge premium over tap water – is supposed to be unaltered between the underground source and the bottle. That is the whole point of it.
If brands like Evian, Vichy and Perrier have been so successful in France and around the world, it is thanks to an appealing image of mountain-sides, rushing streams, purity and health-giving minerals.
Admit filtering the water, and the industry risks breaking the market spell. Consumers might begin to ask what they'd been paying for.
Complicating matters for Perrier and its parent company Nestlé – as well as President Emmanuel Macron's government – is the charge that executives and ministers conspired to keep the affair quiet, covered up reports of contamination, and re-wrote the rules so that Perrier could continue using micro-filtration.
Read more of this report from BBC News.