Is low TDS water bad for you? The question tends to come up in two situations: when someone installs a reverse osmosis filter at home, or when they meet a very low-mineral water at the table. The short answer is that, for anyone with a varied diet, drinking low-mineral water does no harm. The full answer requires separating what water does on the palate from what it represents in nutrition — and acknowledging the one context in which science calls for caution.

What low TDS means

A water's TDS measures, in milligrams per liter, the amount of minerals and salts dissolved in it. On the scale used for fine waters, below 50 mg/L a water is considered Super Low — the lowest mineral band. Between 50 and 250 mg/L sits the Low band, where most bottled mineral waters fall.

Very low values are reached by waters of specific origins: atmospheric waters, captured from air humidity before any contact with soil; glacial waters from recent melt; and waters treated by reverse osmosis or distillation, which remove nearly all salts. Distilled water sits at practically zero.

Where the doubt comes from

The suspicion has three sources. The first is intuitive: if mineral water is associated with health, a water without minerals would seem "empty." The second comes from social media, where claims circulate that low-mineral water "leaches" minerals from the body. The third is legitimate: there is technical literature on the prolonged consumption of demineralized water — and it deserves to be read in the right context.

What the evidence says

The main source of dietary minerals is food, not water. Calcium comes from dairy, leafy greens and legumes; magnesium from whole grains, nuts and vegetables; potassium from fruit and vegetables. Even a medium-mineral water contributes a fraction of the daily intake of these elements. For someone who eats a varied diet, the difference between drinking a 6 mg/L water and a 150 mg/L water is small in the nutritional balance.

In 2005, the World Health Organization (WHO) published a review of the health risks of drinking demineralized water. The document focuses on situations in which desalinated or distilled water becomes a population's sole source of water over long periods — especially where diets are already low in calcium and magnesium. This is why water supply systems based on desalination usually remineralize the water before distributing it.

Context matters. The WHO's concern is with water supply: the water people drink all day and cook with, in populations with restricted diets. That is not the same scenario as a table water served alongside a complete meal.

Does low TDS water "leach" minerals from the body?

It is the most repeated claim and the least supported. The body regulates its balance of sodium, potassium, calcium and magnesium through its own mechanisms, mainly in the kidneys, and replenishes these elements from food. For a healthy person with a varied diet, there is no basis for saying that drinking low-mineral water depletes the body's mineral reserves.

When it does call for attention

Some contexts call for more care with mineral intake — and in them, water is only part of the conversation:

Intense physical exertion and heat. Heavy sweating means losing sodium and potassium. Replacement comes from food and, when needed, from drinks designed for it — not from swapping one water for another.

Very restricted diets. When food is already low in calcium and magnesium, the contribution of water gains relative weight. This is the scenario of the WHO review.

Sole, prolonged consumption of distilled or non-remineralized reverse osmosis water. As drinking and cooking water, every day, over long periods.

Infants. Preparing infant formula follows paediatric guidance, which should prevail over any general rule.

Low TDS at the table

Outside nutrition, low TDS has a clear role: the palate. A Super Low water leaves no mineral weight or residual taste, and so interferes little with delicate dishes, wine and spirits. That is why water sommeliers recommend it at specific moments of a meal — a topic covered in when to serve Super Low waters.

AWA, at 6 mg/L, sits in this band. It is designed for the table — alongside food, which is where minerals come from.

Conclusion

Low TDS does no harm to anyone with a varied diet. The real point of attention is a different one: the sole, prolonged consumption of demineralized water, especially with a mineral-poor diet. As with the opposite case — is high TDS bad? — the number is neither villain nor virtue. It is information about taste and composition, read together with context.