EN
Extensive exploitation of groundwater from quaternary deposits of fluvioglacial origin, reaching annually over 1.5 mln m3 in RetkówStara Rzeka water intake, affected both chemical composition and physical properties of water. Detrimental changes in water quality were manifested mainly by an increased alkalinity, hardness, electrolytic conductivity as well as by raised concentration of iron and manganese ions or sulphates. The value of water alkalinity has increased from below 1 meq/dm3 to over 4.5 meq/dm3 in 1986 and 1994, respectively. Conductivity, strongly related to overall mineralisation of water (Total Dissolved Solids TDS content), over the same period increased on average from about 150 µS/cm to over 550 µS/cm, and in some wells reached nearly 900 µS/cm.