Gold standard for utility performance

Water quality

General information about water

„ thou hast no taste, no colour, no odour; canst not
 be defined, art relished while ever mysterious.
 Not necessary to life, but rather life itself"

(Antoine de Saint Exupéry) 




This literary quotation truly reflects the basic nature of water. No wonder that all the arts, sciences are interested in water. Its significance lays in that some 70.8 percent of the earth's surface is covered with water, thus representing the largest mass of materials. Its amount is practically steady, amounting to ca. 1.4 billion km3.

97.3 percent of this amount is salty seawater, while the rest is sweet water, more than 2 percent of which is present on Earth in the form of ice, a significant amount is present in the stratosphere and in the soil layers, which means that the so-called potable sweet water, that is, waters of the rivers, sweet water ponds and underground water reservoirs represent only 0.6 percent, the distribution of which is imbalanced on Earth.


Water quality

Our Company provides water to the population of Budapest and the surrounding settlements, the quality of which is excellent even in terms of international comparison. Our laboratories perform the analysis of some 11 thousand water samples each year, and evaluate the quality of the produced and delivered water on the basis of physical, chemical, microbiological, bacteriological and radiological features.

The results indicate that the potable water quality in Budapest meets the requirements of both the Hungarian standards and the provisions of the European Union. The quality of potable water is tested also in the laboratory of the public health authority.

Frequently Asked Questions (FAQ) – Our responses

  • What is used for disinfection?

    Water is disinfected with chlorine gas with the help of continuously operating chlorine dispensers, before it is let in the water pipeline. In the case of structures (including wells, reservoirs, water towers) and pipe network sections, bleaching powder or hypo is used for disinfection.
  • What is the ratio of the disinfecting materials added to water?

    In a rate which prevents damage to public health caused by potable water.
    Currently, the measurable chlorine residue is 0.2 mg/l, which meets the recommendations of the health authorities. We may depart from this value only in case the quality of the supplied water is exposed to adverse effects (e.g., flood, pipe burst, etc.).




Free active chlorine


100 mg/l


200 µg/l


50 µg/l


50 mg/l


0,1 mg/l


0,2 mg/l

Total hardness

50-350 mg/l CaO


2500 µS/cm




 Certain chemical components and their roles

  • Iron:

Iron is vital to life, it is a component of haemoglobin and enzymes.

  • Chloride:

Its salts formed with metals – e.g., sodium chloride – are absolutely necessary for the formation of hydrochloric acid of the gastric acid, and to the activation of various enzymes.

  • Nitrite, nitrate:

Water quality parameters indicating impurity: where excessive amounts of fertilizer is used, it dissolves from the soil to the water. Its harmful impact decreases the oxygen absorption capacity of blood, and the water becomes rich in nutrients necessary to the proliferation of certain bacteria (eutrophication).

  • Ammonium:

A water quality parameter indicating impurity: ammonium is generated in the decomposition of organic materials and micro-organisms. It may come from the wash-in of communal and industrial wastewater, therefore, it indicates that water is contaminated.


Order for Water quality survey

The Laboratory of Budapest Waterworks accepts third party orders for accredited sampling, water tests, and assessment of potable water (produced, stored, delivered water, water sold in tanks), underground water (wells, monitoring wells), and artificial baths.

The activity of our laboratory covers accredited survey of physical, organic and non-organic chemical, radiological, microbiological, microscopic biological and toxicology analysis. Sampling and site measurementare performed by our sampling department.

The laboratory is accredited by the National Accreditation Body (NAH-1-0681/2015) in compliance with the requirements of the EN ISO/IEC 17025:2005 standard.

For further information please, refer to Vízplusz (Water-Plus) services >>


Water hardness

The pleasure value of potable water and efficiency of the water used for washing are determined in part by the hardness of water, that is, its CaO (calcium oxide) mg/litre ratio. Water hardness figures indicate that in the region of the capital the water is mostly of medium hardness. It is important to know that the harder the water, the more pleasant flavourit has, but the lesser it is suitable for washing, and our washing machine does not like hard water. In most of the cases – e.g. on the labels of the detergents – water hardness is indicated in terms of the German standard of hardness (nk)*.

  • Very soft water: under 40 CaO mg/litre (4 nk)
  • Soft water: between 40-80 CaO mg/litre (4-8 nk)
  • Medium-hard water: between 80-180 CaO mg/litre (8-18 nk)
  • Hard water: between 180-300 CaO mg/litre (18-30 nk)
  • Very hard water: above 300 CaO mg/litre (30 nk)

In the service area of our Company, the average hardness of potable water is 141 CaO mg/l.

*The German standard for hardness (nk) is one tenth of the CaO mg/litre, so for 141 CaO mg/litre, for example, this value is 14.1 nk (2016).