Reverse-osmosis water and minerals: what the science actually says

It is the classic objection, heard at every trade fair and read under every article: “reverse osmosis demineralises water, it’s bad for your health”. As is often the case, reality is more nuanced than the slogan. Let’s look at what the science actually says.

Yes, RO retains minerals, that is its principle

Let’s start by validating the fact: a reverse-osmosis membrane retains most dissolved salts, calcium and magnesium included. The E400 reverse osmosis unit rejects 96% of dissolved salts and particles. That is precisely its strength: the same barrier that retains minerals also retains pesticide metabolites, PFAS, nitrates and most undesirable substances. You cannot have one without the other, that is physics, not marketing.

Water is not your mineral source

The useful question lies elsewhere: what share of your mineral intake comes from water? Answer: a modest one. Around 90% of mineral intake comes from food, dairy, vegetables, cereals, nuts, not from drinking water. A glass of Lake Geneva water provides a few dozen milligrams of calcium per litre; a yoghurt provides several times more. For someone who eats normally and variedly, RO water creates no mineral deficit.

What the WHO says, and why it is a genuine nuance

The World Health Organization has studied low-mineral waters and recommends adapted mineralisation when demineralised water is a household’s exclusive, long-term drink. It is a serious nuance, to be taken seriously: if all your hydration, drinking, tea, coffee, cooking, runs through the RO unit for years, it is reasonable either to keep some mineralised water in your habits, or to add a remineralisation cartridge at the unit’s outlet. Both approaches are valid; it is a matter of preference and actual usage.

The E400’s case: purity and yield

The E400 ticks the boxes that matter in this debate: its 400 GPD membrane rejects 96% of salts for very pure water, intended for drinking and cooking, coffee aroma restored, neutral ice cubes, vegetables cooked in chlorine-free water. And its recovery rate above 50% makes it a frugal unit: for every litre of pure water, less than a litre goes to drain, markedly better than classic tank-based RO systems.

Conclusion: a legitimate question, an individual answer

The minerals question is neither a myth to sweep away nor a scarecrow to wave about: it is a genuine question whose answer depends on your diet, your usage and your preferences. It is exactly the kind of conversation our technicians have with you during the free site visit, before recommending equipment, not after. In Geneva and the canton of Vaud, EGBT SA installs, tunes and maintains your RO unit; ask us the question, and we will answer it with figures.

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