When we talk about “water hardness”we mean how much the water we drink or use every day is rich in mineral (ions), including calcium (Ca²⁺) and magnesium (Mg²⁺). Obviously, the term “hardness“is used in a figurative way: water, even if rich in calcium and magnesium ions, is not physically hard, but something can change from a chemical point of view. According to the WHO, the hardness of water does not represent a direct health riskbut among other things, hard water tends to release known white limestone deposits which we find on surfaces wetted by the aqueous flow, such as the walls of the toilet, the bottoms of pots, the shower head. Based on the concentration of these ions, water can be defined as hard, soft or medium, but now, the question we ask ourselves is: “what do I need to know?Short answer: it is used to understand the effect of that water in the daily use we make of it at home, allowing us to adopt solutions that improve efficiency and, in some cases, reduce costs.
What does “water hardness” mean?
Water hardness refers to quantity of calcium and magnesium ions dissolved in it (and to a lesser extent other ions). Simply put: the more dissolved calcium and magnesium, the “harder” the water. Even if official regulations (such as those of the World Health Organization) do not establish a sort of “maximum limit” for hardness, because it is not considered a direct health problemit remains a useful parameter that describes the water we use. In reality, there is a distinction in water hardness:
- Temporary hardness: linked to chemical compounds such as calcium or magnesium bicarbonates which can be partially removed by boiling. If we cook a pasta dish, we can be sure that most of the temporary hardness is gone;
- Permanent hardness: linked to more stubborn chemical compounds, such as sulphates, chlorides, calcium or magnesium nitrates, which cannot be eliminated by simple boiling. In short, we eat these together with our pasta!
How to measure water hardness
To quantify the hardness of water there are some real units of measurement which may vary between different countries. Among these, in Italy and other European countries, the most famous are French degrees (°F) or the milligram of calcium carbonate (CaCO3) equivalent per litre (mg/L CaCO3); 1°F corresponds to 10 mg/L of CaCO3 for every liter of water. Based on French degrees, the most used unit of measurement, water is classified as:
- light or sweet: hardness less than 15°F;
- medium hard: hardness between 15 and 30 °F;
- hard: hardness above 30°F.
In practice: if on your bill or analysis report you find for example “total hardness = 25° F”, according to the classification it means that the water is “medium hard”. Knowing it you can evaluatefor example, whether to use specific detergents for hard water and whether to periodically check the taps (or even think about a water softening system).
What is the purpose of knowing the hardness of water?
Beyond the definitions, from a practical/domestic point of view, how can we understand if our water is hard? Enough look around! Limescale streaks on the toilet walls, taps with deposits, residues on the taps or shower heads. Not only that, even the smallest actions, such as washing our hands, can give us clues regarding the hardness of the water in our home: soap, if the water is particularly hard, will form much less foam than expected (this does not mean that it will not clean the dirt, but it will do so to a lesser extent). Although it may seem like something that doesn’t concern us, knowing the hardness of water is useful for two reasons: home, efficiency/savings
Home and daily use
On the domestic environment, however, hard water can have effects more immediate and visible: soaps and detergents “work” more – the calcium and magnesium ions react with the soap, reducing foam and leaving residues. And household appliances (boilers, water heaters, dishwashers) work in worse conditions, because limescale deposits can accumulate which reduce their efficiency, they increase energy consumption and require more frequent maintenance.
Efficiency and savings
Well yes: hard water has an impact on ours too wallet. It is useful to know that if the water is very hard, you might consume more detergent, use more energy to heat it, clean appliances or taps more often, need descale or change components. Knowing the hardness helps you decide whether to install a water softener or a treatment systemor simply use measures such as suitable detergents and periodic descalers, saving without waste. They seem trivial considerations, but putting them together and looking at the long term they can bring benefits in various respects.
Hard water does not pose a health risk
From a health point of view, according to the Drinking Water Guidelines drawn up byWorld Health Organization (WHO), the hardness of water does not represent a problem for most people; at most the concentration of these salts can influence taste and personal preferences. The main health institutions they do not set limits because hard water is not considered a real direct risk. Some studies have found statistical associations between waters richer in calcium and magnesium and a lower incidence of cardiovascular diseases, but be careful: these are results observationalthe results of which are still under debate. It does not mean that “hard water is good for you”, nor that it is useful to increase it on purpose.
At the same time, the opposite idea is not valid either, that is, that limestone “causes kidney stones”: the most common stones are not made of calcium carbonate, but of calcium oxalate and hard water in itself is not considered a direct cause. Only those who are already predisposed can evaluate with a doctor whether to prefer waters less rich in minerals. In short, knowing the hardness of the water is more useful for the well-being of the house than for the body. but it is still useful to know what we are drinking, especially if we have specific personal conditions or particular dietary needs.
