Water hardness

Drinking water in general contains dissolved gases and organic and inorganic substances, which together influence the water quality. One of the indicators of the quality of water is the water hardness parameter. Although the term is obsolete and technically incorrect, the general public and experts alike are familiar with it and the term is still in regular usage. All water contains calcium in a natural form. If water contains a greater concentration of calcium and also magnesium, we call it "hard".

Water hardness depends on the degree of mineral content in the water but it has never been given a single definition. In general, water hardness means the concentration of all high valence cations of alkali earth metals; basically this means a quantity of calcium and magnesium.

There are several degrees of water hardness:

• Very soft;
• Soft;
• Medium hard;
• Hard;
• Very hard.

Both extremes are undesirable for both health and processes, whereas from both viewpoints the optimal degree of hardness can vary.

Calcium content in the water is related directly to the geologic composition of the rocks that the water flows through. This is why water hardness is often different in various geographic areas. Water coming from calcareous formations is harder than water drawn in mostly granite areas.

For better health, we prefer harder water but increasing hardness is only beneficial up to a certain degree. Optimal hardness of drinking water is specified in the drinking water public notice. Calcium, which forms main component of hardness, is in no way detrimental to human health. Quite the contrary - drinking water containing mineral salts of calcium and/or magnesium is recommended for healthy growth and for protection from decalcification. In this way, water from the tap is the simplest everyday source of calcium for the human body.

• A film appears on the top of tea or coffee in the cup
• Aromas of foods and drinks are lost due to a reaction with the calcium carbonate in the water
• Unpleasant taste of the water itself
• According to some sources, water hardness prolongs the cooking time for meat and vegetables

You can prevent the undesirable effects of hard water by adding a few drops of lemon juice or ascorbic acid (a pinch per litre of water), which is available over the counter in pharmacies.

When hard water is heated, the dissolved calcium compounds settle on the walls of the vessels or boilers in the form of a rigid scale.

For water heaters and boilers:

Reduce water temperature to 60 °C. The scale settles much faster at higher temperatures. It is recommended to use water softeners for hard water.

Hard water:

• soap generates less foam and rinses off easily
• leaves whitish scale in pots, dishes and sanitary equipment
• leaves scale in hot water pipes, water heater and other utensils