Is hard water actually healthy for us - the answer to this question.

The hardness of water arises from the presence of dissolved calcium and magnesium ions in various chemical forms. Depending on the predominant components, it is categorized into calcium hardness, magnesium hardness, carbonate hardness (linked to carbonates and bicarbonates), or non-carbonate hardness (attributable to sulfates, chlorides, and nitrates). In the absence of carbonates and bicarbonates, hardness is assessed based on total alkalinity. Additionally, a distinction is made between temporary hardness (removable through boiling) and permanent hardness (persisting even after heating). As a general rule, the higher the concentration of mineral ions, the harder the water. The classification scale is as follows: < 100 mg CaCO₃/L (very soft water), 100–200 mg CaCO₃/L (soft water), 200–350 mg CaCO₃/L (moderately hard water), 350–550 mg CaCO₃/L (hard water), and > 550 mg CaCO₃/L (very hard water).

In an interview granted by Mr. Wojtaszek, a mineral water specialist affiliated with the Polish Magnesological Society, a striking assertion was made: water in its purest form—devoid of any mineral constituents—not only fails to hydrate the body effectively but may actually contribute to dehydration. The critical factor here lies in the presence of electrolytes—compounds such as magnesium, calcium, and sodium—which facilitate the proper absorption and retention of water within tissues. Without these minerals, water instead dilutes the concentration of essential ions in cells, disrupting osmotic balance and impairing physiological hydration. Furthermore, natural mineral waters, whether in their unaltered state or fortified with key trace elements, serve as a vital source of micro- and macronutrients, the demand for which escalates during periods of heightened physical exertion, stress, or monotonous dietary patterns. It is noteworthy that sodium, often vilified in health discourse, is present in mineral water at levels far lower than those found in processed foods (e.g., deli meats or bread); in reality, it plays an indispensable role in maintaining cellular osmotic equilibrium. Additionally, the relative proportions of calcium and magnesium in mineral waters hold both biological significance (with calcium typically predominating quantitatively) and practical implications: they determine water hardness, which in turn affects the risk of corrosion in plumbing systems (in the case of soft water) or the formation of limescale deposits (in the case of hard water).

According to European Union guidelines, optimal drinking water should provide at least 7.5% of the daily requirement for essential trace elements, which qualifies it as beneficial for bodily function. Experts emphasize that the most valuable waters are those with high mineral content—at least 1000 mg of dissolved salts per liter—classifying them as hard water. Research conducted in Japan during the 1960s revealed a significant correlation between the consumption of soft water and an increased incidence of cardiovascular diseases, further validating the advantages of mineral-rich water. While there are circumstances where excessive intake of certain components may be inadvisable, for the majority of the population, regular consumption of hard water serves as an effective means of hydration and mineral replenishment. However, the key lies in making informed choices based on label analysis and maintaining moderation in consumption.