Sofia residents drink one of the purest waters in Europe

Our main priority is to supply pure and healthy potable water.

For the water supply to the capital mainly surface waters from the Rila Mountain are used. “Beli Iskar” and “Iskar” dams collect the water and ensure respectively 20% and 80% of the water for the city. A very small part of the territory of the Municipality of Sofia is supplied with water from local water sources in Vitosha and Plana. 

The water from Beli Iskar Dam and the small water sources is only disinfected with chlorine, and the water from Iskar dam is treated at several stages in the potable water treatment plants in Bistritsa and Pancharevo. The processes provide microbiological treatment of the water, i.e. there are no harmful bacteria for the organism.

In order to keep the good potable qualities of the water along its way from the treatment plants to the customers, it is additionally chlorinated in the reservoirs and across the distribution network of the city. Sofiyska Voda AD uses an automated system for continuous monitoring and control of chlorination in the water supply system of the city.

We also strictly control the other water parameters along the whole way of the water to customers. This control is carried out by the Laboratory Testing Centre of Sofiyska Voda AD in partnership with Sofia Regional Inspectorate on Public Health Protection and Control. In this way all water quality parameters are strictly monitored and they are fully compliant with the legislative requirements in the country.

If you have some suspicions about the quality of the water in your home, you can obtain information or submit a signal at telephone number 0700 121 21. An employee from the laboratory of Sofiyska Voda AD will take a sample wherever the point is across the network of the capital and make a relevant analysis. Within 48 hours you will receive information about the results, and in case there is a deviation from the standards, we will urgently undertake measures to remove the reasons for worsening the water quality parameters.

The most frequent reason for that is the old plumbing installation of the building. However, the owners of the residential buildings take care of setting it in order.

Soft water
Potable water at the territory of Sofia Municipality is soft. It is with very low content of calcium and magnesium ions and it does not deposit scale. Their concentration in the water is 10-12 times less than the standard for potable water (standard: 12 mgequiv. /l, concentration in Sofia: 0,9 – 1,2 mgequiv./l).

Stages of Water Treatment in the treatment plants:
1. Chlorine is added to water so that the organic material is oxidized and the bacterial mass in it destroyed;
2. If necessary, reagent (coagulant) is added, and with it the solid substances are consolidated and are easily held by the filters at the subsequent stage of treatment;
3. The water is filtered over a layer of quartz sand;
4. Second chlorination of water at the outlet of the plant. In this way the optimum contents of residual chlorine is ensured, which is required for prevention of secondary bacterial pollution of water.

Chlorination
In order to keep the water clean and with the required potable qualities, chlorine is added to it. With the chlorination, as means of disinfection, the harmful bacteria or viruses are destroyed. The quantity of the chlorine is high enough to destroy the microorganisms and at the same time low enough to be completely harmless to human health.

Legislative requirements
They are regulated with Ordinance No 9/16.03.2001 of the Ministry of Environment and Water adapted to the European Directive on the quality of water.

Indicators of the water
The Laboratory of Sofiyska Voda controls the quality of the potable water and monitors its indicators:
Organoleptic – taste, smell;
Physical and chemical – рН, turbidity, electrical conductance, colour, permanganate oxidization, iron, manganese, aluminum, ammonium ions, nitrates, nitrites, free chlorine, chlorides, total hardness, calcium, magnesium, sulphates, phosphates, fluorides, sodium, zinc, copper, cadmium, lead, chromium, nickel, selenium, antimony, arsenic, boron, cyanide;
Microbiological – colony count, total E-coli, fecal E-coli, enteroccoci , clostridium perfringens, salmonella; 
Hydrobiology– phytoplankton, zooplankton, nematode, seston.

For surface water sources the indicators that are determined are phenols, compounds that are active on the surface, the biological oxygen demand /BOD/ and chemical oxygen demand, dissolved oxygen, and suspended solids, total nitrogen content.

The way of water to customers
Sofiyska Voda AD’s laboratory controls the quality of:

• the raw non-treated water from the water sources – the Iskar Dam, Beli Iskar Dam, the water at the inlet of the two treatment plants, other surface water resources for domestic needs.
• the water at the outlet of all reservoirs (microbiological parameters).
• the water in the network - 78 permanent points for sample taking, as the selection of the points and the periodicity of sample taking comply with the density of the population and were agreed with the Sofia Regional Inspectorate on Protection and Control of the Public Health;