Are There Still Enough Minerals in Filtered Water?

Some people worry that a water filter also removes important minerals, leading to a deficiency in essential nutrients. But this concern is unfounded, because we obtain practically all of our mineral requirements through food.

Water Contains Almost No Minerals

Tap water or mineral water does contain minerals (e.g., calcium, magnesium, sodium), but in very small amounts compared to what you get from food.

Example:
Calcium: A "hard" mineral water may have about 150 mg of calcium per liter. Your daily requirement is around 1,000 mg.

Magnesium: Even mineral-rich water has about 50 mg per liter. Requirement: approx. 300-400 mg.

Potassium: In water almost nothing (<10 mg/L). Requirement: 3,500 mg/day.

So to cover your calcium, magnesium and potassium needs from water alone, you would roughly need:

Calcium: about 7 L water/day (with very calcium-rich water)

Magnesium: about 8 L water/day

Potassium: over 350 L water/day (practically impossible)

And this is only part of the essential minerals. Trace elements like iron, zinc, selenium, etc. are usually present in water only in trace amounts.

Even if you drink exclusively very mineral-rich water, you might cover part of your calcium and magnesium needs. For everything else you would theoretically have to drink hundreds of liters - which is physiologically impossible (you'd already risk water intoxication at 5-10 L water/day).

Overview: Mineral Requirements vs. Estimated Tap Water in Thailand

Mineral	Assumed Daily Requirement (RDI)	Estimated Concentration in Thailand's Tap Water (mg/L)	Liters of Water Needed to Cover RDI from Water Only	Comment
Calcium (Ca)	1,000 mg	35 mg/L	approx. 29 L	Ca levels vary; 35 mg/L equals soft to moderately hard water.
Magnesium (Mg)	300 mg	7 mg/L	approx. 43 L	Mg lower than Ca; depends on region.
Potassium (K)	3,500 mg	2 mg/L	approx. 1,750 L	Potassium in tap water practically negligible.
Sodium (Na)	1,500 mg	15 mg/L	approx. 100 L	Na values vary widely (network, proximity to sea, supply source).
Iron (Fe)	10 mg	0.05 mg/L	approx. 200 L	Iron in drinking water usually very low (higher values problematic).
Zinc (Zn)	10 mg	0.02 mg/L	approx. 500 L	Trace amount - not practical to cover needs from water.
Selenium (Se)	55 µg (0.055 mg)	0.001 mg/L	approx. 55 L	Selenium very low and strongly location-dependent.

Methodology & Sources

• There are hardly any publicly available, detailed measurements specifically for Hua Hin or other individual places in Thailand. Instead we used: a) studies on mineral content in Thai drinking water (e.g., measurements from Bangkok / regional studies), b) Thai drinking water standards, and c) local reports on water quality as the basis and made conservative estimates.
• Main sources (selection): studies on minerals in Thai drinking water (measurements / averages), the Thai drinking water standards (e.g., WEPA overview) as well as local articles about the Hua Hin drinking water situation. These sources show that Ca/Mg are present, but many other nutrients occur only in traces.
• Calculation: Liters = RDI (mg) / Concentration (mg/L). Values rounded and shown as estimates.

Important Notes / Conclusion

• Even with conservative, relatively high estimates for calcium and magnesium, you would have to drink dozens of liters of tap water per day to cover these nutrients from water alone - this is medically not advisable (hyponatremia / water intoxication).
• For potassium, zinc, iron and many trace elements, the required water amounts are practically impossible (hundreds to thousands of liters).
• Tap water can make a small contribution to mineral intake (especially with hard water), but it in no way replaces food (calories, protein, vitamins, essential fatty acids, etc.).

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