Is Swiss tap water enough to stay properly hydrated?
by AUA Hydrate
Turn on the tap, fill a glass. In Switzerland this is one of the most ordinary gestures there is — and the water that comes out is among the most closely monitored in the world. Hence a question that keeps coming back: if our water is that good, why add anything to it? The honest answer has two parts. Most of the time, you should add nothing at all. And there is exactly one exception — which has nothing to do with the quality of the water.
⏱ The essentials in 20 seconds
- Swiss tap water delivers calcium (41 to 96 mg/l) and magnesium (3.7 to 8.9 mg/l). That is not nothing.
- It contains almost no sodium (1.7 to 7.6 mg/l) and no potassium (1.0 to 2.6 mg/l).
- Yet sodium is exactly what sweat carries away: 200 to 2,000 mg per litre — a hundred to a thousand times more than the tap puts back.
- Day to day, tap water is plenty. The moment you sweat heavily, it no longer makes up the difference.
What your tap water actually contains
Four Swiss people in five drink water drawn from groundwater and springs; the rest comes from lakes. Chemically this water is not « pure »: passing through rock, it picks up dissolved minerals. The typical ranges measured in Switzerland:
| Mineral | Per litre of tap water | What it does |
|---|---|---|
| Calcium | 41 to 96 mg | Contributes to normal muscle function |
| Magnesium | 3.7 to 8.9 mg | Contributes to the reduction of tiredness and to normal muscle function |
| Sodium | 1.7 to 7.6 mg | It is what holds water where the body needs it |
| Potassium | 1.0 to 2.6 mg | Contributes to normal muscle function |
Two lines stand out. Calcium and magnesium are genuinely present — a litre of hard water can cover a meaningful share of the daily calcium requirement. Sodium and potassium, on the other hand, are barely traces.
Three Swiss households in four drink hard water. That is good news.
Hardness here is measured in French degrees (°fH): below 7 °fH water is very soft, above 42 °fH very hard. 75 % of Swiss households receive hard to very hard water. Limescale in the kettle aside, that is a nutritional advantage: hardness is made of precisely those calcium and magnesium ions.
In other words, if you live in a limestone region — the Plateau, much of French-speaking Switzerland — your tap is already a source of minerals that is widely underestimated. We cover each one in the 10 essential actives.
The one place tap water falls behind: sweat
Sweat is not water. It is salt water. And the comparison, litre for litre, is striking:
| Per litre | What the tap gives back | What sweat takes away |
|---|---|---|
| Sodium | 1.7 to 7.6 mg | 200 to 2,000 mg |
| Potassium | 1.0 to 2.6 mg | 80 to 320 mg |
A ratio of one hundred to one thousand for sodium. Drinking a litre of tap water after sweating a litre returns the volume without returning the salt. And this is where the mechanism turns against you: water drunk without minerals dilutes what you have left, and part of it leaves through the kidneys instead of staying in the tissues. We covered this in why water alone is no longer enough.
💡 The AUA tip: the simplest marker is still the white ring. If your shirt or your temples leave a whitish mark as they dry, you lose a lot of sodium. Only then will water alone fall short — see what to drink before, during and after exercise.
Should you buy bottled mineral water?
For most situations, no — and we have no interest in telling you otherwise. Swiss tap water is monitored continuously, costs roughly a thousand times less per litre, and spares the transport of bottles.
Sodium-rich mineral waters do exist, but they are rare, expensive, and their taste puts many people off. As for filter jugs, they remove limescale: they lower the mineral content rather than raising it.
When it matters — and when to stop thinking about it
- ☕ An ordinary office day: the tap is enough. The benchmarks are in how much water per day.
- 🏃 More than an hour of effort, or heavy sweating: volume alone is no longer enough, you need the salt too.
- 🥵 Heatwave, sauna, physical work outdoors: same logic — see extreme heat.
- 🤒 Significant digestive losses: that is no longer everyday hydration — speak to your doctor or pharmacist.
The rest of the time, drink your tap water without giving it a thought. It is one of the few areas where Switzerland has nothing to envy anyone.
Where AUA Hydrate fits in
One stick of AUA Hydrate dissolved in 500 ml of tap water delivers 10 actives — six electrolytes including sodium, potassium and magnesium, two trace elements and two vitamins — for 2 kcal and no sugar. Formulated in Switzerland by nutritionists.
It is not a replacement for tap water: it is what you add on the days you sweat. Every other day, the plain glass does the job perfectly.
Your tap water, better on effort days
Pick your flavour from our three tastes — strawberry, peach, lemon.
Frequently asked questions
Is Swiss tap water really safe?
Yes. It is tested regularly and ranks among the most closely monitored foodstuffs in the country.
Should you boil water to remove limescale?
Boiling precipitates part of the limescale, and therefore removes calcium. The benefit is domestic, not nutritional.
Is soft water worse than hard water?
Neither better nor worse for hydration. Soft water simply delivers less calcium and magnesium.
Does an electrolyte stick replace a glass of water?
No, it is added to it. The stick dissolves in 500 ml of water: volume stays the base, minerals are the complement.
