1. water hardness pH PO 4 3- NO 2 -, NO 3 - NH 4 + Fe

2. WATER HARDNESS Water hardness is caused by divalent ions, especially Ca 2+ and Mg 2+. The measure for water hardness is 1°d (=10mg CaO/L water). Classification: 0 – 4 °d…. very soft water 4 – 8 °d…. soft water 8 – 12 °d…. medium soft water 12 – 18 °d…. pretty hard water 18 – 30 °d…. hard water over 30 °d …. very hard water

4. Our results SAMPLEWater hardness School tap water11 Rahtel tap water3 Vuhred tap water7 Šoštanj tap water10 Spring Velenje9 Spring Šoštanj6 Velenje lake18 River Homšnica4

5. pH pH is criteria of acidness and baseness of water. pH = -log [H 3 0 + ] [H 3 0 + ] > 10 -7 => pH < 7 (acid) [H 3 0 + ] = 10 -7 => pH = 7 (neutral) [H 3 0 + ] pH > 7 (base)

7. Our results SAMPLEpH School tap water8 Rahtel tap water6,5 Vuhred tap water7 Šoštanj tap water8 Spring Velenje7,5 Spring Šoštanj7,5 Velenje lake8 River Homšnica7,5 natural water has pH between 6 and 8 drinking water => pH = 6,5 – 8,5 (EC rules)

8. PO 4 3- Natural unpolluted water contains less than 0,1 mg/L of all the PO 4 (higher concentrations are caused by human pollution). Sources of pollution: phosphoric manures washing and detergents phosphating (transformation of metal surfaces into phosphates as a protection from rusting)

10. Our results SAMPLEPO 4 3- School tap water0,3 Rahtel tap water0,5 Vuhred tap water0 Šoštanj tap water0,5 Spring Velenje0,5 Spring Šoštanj0,5 Velenje lake0,1 River Homšnica0,5 drinking water => PO 4 3- = 0,6 mg/L (EC rules)

11. NO 2 -, NO 3 - Nitrates (NO 3 - ) are the major polluters of ground water and also of many fluent and influent waters. Sources of pollution: artificial manures intensive stockbreeding poor infrastructure (sewage) The functioning key of nitrates is transformation into nitrites (NO 2 - ).

13. Our results SAMPLENO 3 - NO 2 - School tap water100,2 Rahtel tap water00,2 Vuhred tap water100,2 Šoštanj tap water100,2 Spring Velenje100,2 Spring Šoštanj100,2 Velenje lake100,2 River Homšnica100,1 drinking water => NO 3 - = 25 mg/L (EC rules) drinking water => NO 2 - = max. 0,1 mg/L (EC rules)

14. NH 4 + The presence of ammonium in water shows that the water was in contact with rotting organic materials, fecals..

15. Our results SAMPLENH 4 + School tap water0,05 Rahtel tap water0,2 Vuhred tap water0,2 Šoštanj tap water0,2 Spring Velenje0,05 Spring Šoštanj0,05 Velenje lake0,2 River Homšnica0,2 drinking water => NH 4 + = 0,05 mg/L (EC rules)

16. Fe Iron is often presented in water. It represents over 5% of Earth bark and by water absorbing it, iron comes in the water. It causes a lot of troubles rusted stains on clothes (washed in washing machine) iron coating on pipes

18. Our results SAMPLEFe School tap water0,3 Rahtel tap water0,6 Vuhred tap water0,2 Šoštanj tap water0,4 Spring Velenje0,1 Spring Šoštanj0,1 Velenje lake0,3 River Homšnica0,4 drinking water => Fe = max. 2 mg/L

19. WATER IN SLOVENIA To conclude: all pH values of drinking water are according to EC rules all PO 4 3- values meet EC rules NO 2 - and NO 3 - ground water that contains over 25 mg NO 3 - /L water of Drava field water of Ptuj field water of Spodnja Savinjska valley water of Prekmurje field Only both sources and school tap pipe water are according to NH 4 + value all Fe values meet EC rules