Mineral Water Guide
How to read a water label
(Without a chemistry degree)
Every bottle of natural mineral water lists its mineral composition on the label. These values are expressed in mg/L (milligrams per liter) - meaning how many milligrams of a substance are dissolved in one liter of water.
Because most people drink, on average, almost two liters of water per day, even small differences in mineral content can add up over time. Understanding a few key parameters makes it much easier to interpret what those numbers actually mean.
Key Parameters on a Water Label
These are the six values that matter most when comparing mineral waters:
| Parameter | Unit | Why it matters |
|---|---|---|
| Fixed Residue (at 180°C) | mg/L | Total dissolved minerals - the single best indicator of how mineral-rich a water is |
| Sodium (Na⁺) | mg/L | Contributes to daily salt intake - ranges from near zero to over 1,000 mg/L |
| Calcium (Ca²⁺) | mg/L | Supports bone structure and muscle function - can range from <10 to >400 mg/L |
| Magnesium (Mg²⁺) | mg/L | Involved in muscle activity and energy - one of the most variable minerals |
| Bicarbonate (HCO₃⁻) | mg/L | Influences taste and mineral balance - gives water a rounder feel |
| Nitrates (NO₃⁻) | mg/L | Monitored for safety under strict EU limits |
Why the Numbers Matter
At first glance the values on a label may seem small. But mineral waters vary enormously:
Calcium
from <10 to >400 mg/L
Sodium
from near zero to >1,000 mg/L
Magnesium
from <1 to >100 mg/L
Fixed residue
from 14 to >7,000 mg/L
Over months or years of daily consumption, these differences meaningfully influence total mineral intake. Reading the label is the simplest way to understand what you are actually drinking.
Other Minerals You May Find on the Label
In addition to the key parameters above, labels may list other naturally occurring minerals. These reflect the geological layers the water passes through:
| Parameter | Unit | Why it matters |
|---|---|---|
| Potassium (K⁺) | mg/L | Contributes to electrolyte balance, though usually present in small amounts |
| Sulfate (SO₄²⁻) | mg/L | Can influence taste, giving water a slightly drier character at higher levels |
| Chloride (Cl⁻) | mg/L | Contributes to overall mineral balance and can slightly affect taste |
| Fluoride (F⁻) | mg/L | Naturally present in some waters and monitored due to regulatory limits |
| Silica (SiO₂) | mg/L | Commonly found in mineral waters, contributing to their natural composition |
These minerals typically vary less between waters and play a secondary role in everyday water selection. To learn more, see our article on other minerals in mineral water.
Once you can read the label, the next step is How to choose the right mineral water.
Key takeaway
A water label tells you exactly what is in your water. The key values to look at are fixed residue, sodium, calcium, magnesium, bicarbonate and nitrates. Once you understand these six parameters, you can compare any two waters in seconds - and choose the one that fits your preferences.
FAQ
What does mg/L mean on a water label?
mg/L stands for milligrams per liter. It indicates how many milligrams of a specific mineral are dissolved in one liter of water.
What is the most important value on a water label?
Fixed residue (total mineralization) gives the best single overview of how mineral-rich a water is. Beyond that, sodium, calcium, magnesium and bicarbonate are the key parameters to compare.
Why do mineral water labels show different values?
Each mineral water comes from a unique geological source. The type of rock, depth and underground flow path determine which minerals dissolve into the water and in what concentrations.