no anomalous changes temperature °C hydrogen ion concentration pH unit 7.4 7.3 7.5 > 6.5 and < 9.5 electrical conductivity µS/cm at 20 °C 560 595 896 <2500 chlorides mg/l Cl 6.6 5.9 46.8 <250 sulphates mg/l SO4 13.7 11.31 66 <250 calcium mg/l Ca 100.6 115.9 exempt (*) not required magnesium mg/l Mg 19.0 17.1 exempt (*) not required sodium mg/l Na 4.7 3.6 37.0 <200 potassium mg/l K 2.0 1.23 exempt (*) not required hardness °F 32.9 36 35.6 (**) free residual chlorine mg/l Cl2 0.15 0.19 0.15 (***) alkalinity mg/l CaCO3 435 358 exempt (*) not required calculated fixed residue mg/l 408 426.7 612 (****) nitrates mg/l NO3 3.5 3.8 37.9 <50 nitrites mg/l NO2 <0.05 0.1 <0.03 <0.50 ammonia mg/l NH4 <0.10 <0.1 exempt (*) <0.50 fluorides mg/l F 0.14 0.15 0.5 <1.50 bicarbonates mg/l HCO3 400 436.3 exempt (*) not required total organic carbon mg/l C 0.58 0.53 exempt (*) no anomalous changes iron µg/l Fe 11.8 16.1 <20 <200 copper mg/l Cu 0.003 0.00 <0.01 <1.0 lead µg/l Pb 0.4 0.3 2 <10 cadmium µg/l Cd <0.2 <0.2 <2.0 <5.0 water system allows the quality safety level to be kept high.