It is common knowledge that household water filtration systems cause water demineralisation. However, the available literature lacks data concerning to what extent filters decrease concentrations of chosen mineral components in water. The aim of the study was to estimate the effect of filters mounted on domestic water intakes on the changes in selected water properties. Water samples filtered in a reverse osmosis system and not enriched by further mineralization were taken for the study. Total hardness, concentrations of magnesium, calcium, chloride and nitrate ions and water pH and conductivity were determined after filtration and compared with the same parameters in water from the waterworks. Randomly chosen water samples used for the study were taken from sites in north-eastern Poland. The analyses were carried out according to current standards. All the studied samples of unfiltered water met the drinking-water quality standards laid down by the Regulation of the Minister of Health. In the study, it was demonstrated that water filters significantly decreased electrolytic conductivity as well as the concentrations of magnesium and calcium ions (decisive for water hardness) and chlorides. The analysed filters also increased water acidity. Drinking filtered water decreases the share of water in the recommended dietary allowance (RDA) for calcium and magnesium and may result in many diseases, which is discussed in the paper. No positive effect of water filters on nitrate concentrations was found. The authors proved that installing household water treatment devices seems unnecessary, especially when water is purchased from municipal waterworks and tested as safe for human consumption.

20.1.2015