Water Quality Data
DRINKING WATER QUALITY INDICATORS
The characteristics of drinking water that determine its quality are divided into three main groups—physical, chemical (including radiological), and biological—and are subject to continuous and regular monitoring and control.
Some of these parameters, which are highly sensitive to changes in water composition, are used as reliable indicators for tracking trends and quickly detecting emerging changes. They are monitored at a frequency that ensures continuous information on the quality of the drinking water supplied to the water distribution network.
pH
pH is a numerical value used to determine the acidity of water. Water quality regulations specify that the pH of water in the water supply network of populated areas must be between 6.5 and 9.5 pH units
.Electrical Conductivity
Conductivity characterizes water’s ability to conduct electricity and is an indicator of the concentration of dissolved substances in it, i.e., its mineralization.
The limit value for the electrical conductivity of drinking water is 2000 µS/cm.
Water with high conductivity does not pose an immediate risk to human health, but it can cause corrosion in plumbing systems, limescale buildup, a mineral taste in drinking water, and other issues
.Turbidity
Turbidity is a measure of the degree to which water has lost its transparency due to the presence of suspended particles. The more suspended particles there are in the water, the cloudier it appears, and the higher the turbidity value.Turbidity
levels in drinking water must be acceptable to consumers, and no unusual changes should be observed. According to the World Health Organization, the turbidity of drinking water should not exceed 5 NTU
.Taste, Odor
Taste and odor are characteristics of drinking water that result from the specific properties of the water source or from water treatment for disinfection.
Drinking water must have levels of these characteristics that are acceptable to consumers and remain consistent. Not all changes in the taste and odor of drinking water pose a health risk
.Color
The color of water is caused by the absorption or reflection of light by suspended and dissolved particles; therefore, the more of these particles there are, the more color the water has. The main sources of color in water are humic and organic materials, iron complexes, and the bacterial action on dissolved manganese particles.
Drinking water has no visible color because most people can visually detect a color above 15 color units in a glass of water. Color levels below 15 color units are acceptable to consumers
.Residual free chlorine
Chlorine (Cl2) does not occur naturally in water but is added to it for disinfection. The residual chlorine concentration maintained in the water is sufficient to ensure its good sanitary quality. The limit values for residual free chlorine in drinking water are 0.3–0.4 mg/l.
Aluminum
Natural aluminum, as well as aluminum salts used as coagulants in drinking water treatment, are the main sources of aluminum in drinking water.
The permissible concentrations of aluminum in drinking water are 200 µg/l.
Therefore, treatment processes are optimized to minimize the amount of residual aluminum entering the distribution system
.Iron
Iron is a naturally occurring element in water from surface (reservoirs) and groundwater sources. It may also be present in drinking water as a result of corrosion of iron water pipes.
Regulatory documents set a limit for iron content in drinking water at 200 µg/l, as exceeding this value may affect the color, taste, and odor of the water.However, this does not mean that drinking water containing iron above this level will lead to health problems. The World Health Organization reports that drinking water with iron levels up to 2000 µg/l (i.e., up to 10 times the legal limit) does not pose a significant risk to the population
.Ammonium ions, Nitrates and Nitrites
Ammonium ions, nitrates, and nitrites are nitrogen compounds that are an integral part of the nitrogen cycle in the environment; nitrates occur naturally in some groundwater. Elevated concentrations of these three forms of nitrogen in water used for drinking and domestic purposes result from the improper use of nitrogen-based mineral fertilizers in violation of good agricultural practices, failure to comply with requirements regarding the collection, storage, and disposal of manure in livestock farming, and the discharge of wastewater, septic tank effluent, and other sources.
When present in concentrations permitted by law, the ammonium ions, nitrates, and nitrites found in drinking water are harmless
.Coliforms
Coliform bacteria are organisms that occur naturally in the environment. They are generally not dangerous and do not cause disease. However, their presence in drinking water is an indicator that pathogenic organisms may be present in the water supply system.*
Escherichia coli*
Escherichia coli, or E. coli, is a type of fecal coliform bacterium commonly found in the intestines of animals and humans. The presence of Escherichia coli in drinking water is a clear indication of contamination with sewage or animal waste. According to European and national legislation, the presence of E. coli in drinking water is not permitted
.Fecal enterococci
Enterococci are fecal bacteria that can enter untreated water if agricultural and livestock facilities are improperly located relative to groundwater sources. Since enterococci can persist in faucets, it is important to prevent contamination of both the water distribution system and the building’s plumbing system
.Microbial Count at 22 °C
The microbial count is an indicator of water quality that provides information about its overall, nonspecific bacteriological contamination. It is expressed as the total number of bacterial colonies (Colony Forming Units—CFU) per 1 mL of water.
REGULATION No. 9 of March 16, 2001, on the quality of water intended for drinking and domestic use requires that the values for this parameter show no significant fluctuations from the typical value for the water in question.
DRINKING WATER MONITORING
In compliance with the requirements for providing the population with safe and clean drinking water, introduced into Bulgarian legislation by REGULATION No. 9 OF MARCH 16, 2001 ON THE QUALITY OF WATER INTENDED FOR DRINKING AND DOMESTIC USE, VIK EAD Burgas continuously monitors the quality of the water supplied to all water supply zones operated by the Company.
Monitoring is carried out in accordance with the Drinking Water Monitoring Program for Burgas District, which specifies the water supply zones, populated areas, and monitoring points, as well as the frequency of monitoring and the parameters analyzed. The program is prepared annually by VIK EAD – Burgas, approved by the Regional Health Inspectorate (RZI) – Burgas, and strictly implemented by the Company. The goal is to ensure that the measures implemented to control risks to human health throughout the entire water supply system—from the catchment area through water abstraction, treatment, and storage to distribution—are effective and that the water supplied through the water distribution network is safe and clean.
Sampling and analysis of drinking water are performed by testing laboratories accredited in accordance with BDS EN ISO/IEC 17025, using testing and sampling methods that meet the requirements of Annex No. 3 to Article 9, paragraph 13 of Regulation No. 9 of March 16, 2001, on the quality of water intended for drinking and domestic use.
INFORMATION ON DRINKING WATER QUALITY
Information on the quality of drinking water supplied by VIK EAD – Burgas is provided to consumers in the form of reports containing data on: the locality and monitoring point; the area and type of water supply; the date of sampling; and the results of the laboratory analyses performed. The
reports are prepared monthly and published on the Company’s website. They reflect the quality of the drinking water at the specific time of sampling at the designated monitoring point.