CHEMICAL COMPOSITION AND ASSESSMENT OF DRINKING WATER QUALITY: LATVIA CASE STUDY

Assessment of drinking water quality in seven largest Latvia drinking water supply systems (Riga, Daugavpils, Liepaja, Ventspils, Jelgava, Jurmala, and Rezekne) in 2008 using mathematical statistical processing of chemical composition data and calculation of drinking water quality indexes are carried out. Daugavpils, Liepaja, Ventspils, and Rezekne drinking water supply systems are assessed as excellent, Riga and Jurmala - good, but Jelgava - fair quality of drinking water. In Jelgava drinking water sulphate concentration exceed the accepted maximum permissible value (MPV) for 97 mg/dm(3) and in Jurmala - for 26 mg/dm(3). Besides, high values of total iron (1.15 +/- 0.54 mg/dm(3)) and turbidity (14.2 +/- 7.2 nephelometric turbidity units) were obtained also in Jelgava drinking water. Relative high concentration of aluminum in Liepaja drinking water (0.2 mg/dm(3)) takes place that achieves the MPV (0.2 mg/dm(3)). In all analyzed drinking water the concentrations of Hg, Cd, Pb, Cu, Ni, Cr (total), BrO3- and trihalomethanes (total) were observed in the level of their determination or less than it or concentration changes were observed only in some cases that are significantly less than their MPV. In general drinking water quality of the largest Latvia drinking water supply systems is assessed as agreeable to the existed legal norms.