Regional pollution stems from the use of fertilizers and pesticides in agriculture which causes an increase in the content of chlorides in underground waters, exceeding by 4-6-fold their background concentrations. The other contributors to regional pollution are sulphates, nitrates by a factor of 2-4 and 6-10 respectively. Regional pollution is also affected by radionuclide fallout due to the accident at the Chernobyl nuclear station. Though radioactivity in ground waters does not exceed the permissible national level of 18 Bq/dm3, it is 1000 times higher than the natural background radiation level.
The local underground water pollution occurs in areas where animal breeding complexes are operating, in the fields affected by their runoff, in storage facilities for mineral fertilizes and pesticides where maximum permissible concentrations (MPC) are exceed by a factor of 2-3 for chlorides, sulphates and nitrites, 4-5 for nitrates, and 200 for ammonia.
In industrial-urban agglomerations underground water pollution takes place on industrial sites, at waste disposals, treatment areas, dumping grounds and on sites of leakages from industrial and household sewerage. In proximity to pollution sources solid residual in underground water reaches up to 2-7 g/dm3 (f. e. at the Gomel chemical plant, etc.) A critical situation persists in the area around the Soligorsk potassium chloride complex, where salinization by salt dumping and tailing storage grounds remains a problem spreading to the depth of more than 100 m in depth, as well as pollution on sites of rock subsidence in the mining area. Pollution of soil and underground waters by chlorides is the result of wind erosion of saline solid waste.
In general the sanitary-hygienic state of underground waters at the operating withdrawals meets the national set of requirements, except for concentrations of specific elements. Water deterioration in some wells is caused by the presence of industrial objects not answering the design requirements as well as by the unsatisfactory state of sanitary protection zones.
Within the areas of withdrawals underground waters are characterized by high content of manganese that reaches 0,1-0,3 mg/dm3 (MPC=0,1 mg/dm3), and 0,5 mg/dm3 in specific wells. The effect of ferrous compounds, with concentrations of 0,4-3,0 mg/dm3 compared to its MPC of 0,3 mg/dm3 is recorded almost everywhere. Their maximum concentration reaches up to 5-8 mg/dm3, though as a rule it is connected with natural hydrogeological conditions.
High concentration of nitrates (45,6-75,1 mg/dm3) in the waters of some single wells in certain Minsk withdrawals (MAC = 45,0 mg/dm3) could be explained by their location within the urban development areas and non-compliance with the sanitary standards. High concentrations of calcium and magnium in water (up to 8-10 mg-eq/dm3), responsible for underground water pollution in the withdrawals developed areas is pointing to local contamination of underground waters. High content of ammonia (6-8 mg/dm3) is recorded in water of some operating wells.
Due to inflow of mineralized water into withdrawals in some wells, an increase in dry residue (931,6-1062 mg/dm3), as well as high chloride concentrations (346,5-419,5 mg/dm3) are observed there. Underground pollution with lead occurs only in specific cases. The lead concentration in water in these cases reaches 0,06-0,08 mg/dm3.
Water for urban supply is mainly withdrawn from underground sources. To ensure centralized water supply for 85 cities and towns, as well as for industrial centers, 147 group withdrawals are used. Only inhabitants of Polotsk, partially Grodno, Minsk and Gomel are provided with drinking water from surface withdrawals. Water losses with transportation do not exceed 6% of the whole withdrawal (0,12 km3).
A great number of wells (14%) in the country do not have the water protection zone of strict control and about 80 % of communal pipes do not have required treatment facilities (especially for removing the ferrous compounds).
Underground water quality in operating wells generally meets national standards for potable water but most withdrawals fail national standards for softness, color, turbidity, as well as ammonium, ferrous and manganese content.
Laboratory analyses undertaken by the National Sanitary-Epidemiological Service show that some 30% of water samples from sources of the centralized supply of industrial and drinking water do not meet sanitary standards. The main reason for such aberrations is ferrous effect that leads to exceeding the standards for color and turbidity. Almost half of the tested samples nationwide failed the national standard for «Potable Water» by the iron content (MPC=0,3 mg/dm3).
Water quality checks according to microbiological indices show that in 2,4 % of the total tested samples Coli-index exceeded the standard recommended by the World Health Organization (9 points).