Water hardness

The quality of the potable water and the effectiveness of water used for washing are partly defined by the hardness of the water, i.e. the CaO (calcium-oxide) mg/litre ratio. Water hardness figures indicate that the consumers in the capital are provided with more or less medium hard drinking water. The harder the water, the better is tastes, but the less effective it is for washing clothes. In most cases ? like on the packaging of washing powders ? water hardness is given in what is known as the German degree of water hardness (nk)*.

• Soft: below 100 mg of CaO/litre (10 nk)
• Hard: between 180-300 mg of CaO/litre (18-30 nk)
• Very hard: above 300 mg of CaO/litre (30 nk)

The average hardness of water supplied in the service area of our company is 144 mg of CaO/l

*The unit of the German degree of water hardness (nk) is one tenth of 1 mg of CaO/litre, in other words 144mg CaO/litre translates to 14.4 nk.

Water quality and water hardness by districts