•water hardness
•pH
•PO43•NO2-, NO3•NH4+
•Fe
WATER HARDNESS
 Water hardness is caused by divalent ions, especially Ca2+ and
Mg2+.
 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
Our results
SAMPLE
Water hardness
School tap water
11
Rahtel tap water
3
Vuhred tap water
7
Šoštanj tap water
10
Spring Velenje
9
Spring Šoštanj
6
Velenje lake
18
River Homšnica
4
pH
 pH is criteria of acidness and baseness of water.
 pH = -log [H30+]
 [H30+] > 10-7 => pH < 7 (acid)
 [H30+] = 10-7 => pH = 7 (neutral)
 [H30+] < 10-7 => pH > 7 (base)
Our results
SAMPLE
pH
School tap water
8
Rahtel tap water
6,5
Vuhred tap water
7
Šoštanj tap water
8
Spring Velenje
7,5
Spring Šoštanj
7,5
Velenje lake
River Homšnica
• natural water has pH between 6 and 8
• drinking water => pH = 6,5 – 8,5 (EC rules)
8
7,5
PO4
3-
 Natural unpolluted water contains less than 0,1 mg/L of
all the PO4 (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)
Our results
SAMPLE
PO43-
School tap water
0,3
Rahtel tap water
0,5
Vuhred tap water
0
Šoštanj tap water
0,5
Spring Velenje
0,5
Spring Šoštanj
0,5
Velenje lake
0,1
River Homšnica
0,5
• drinking water => PO43- = 0,6 mg/L (EC rules)
-,
NO2 NO3
-
 Nitrates (NO3-) 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 (NO2-).
Our results
NO3-
NO2-
School tap water
10
0,2
Rahtel tap water
0
0,2
Vuhred tap water
10
0,2
Šoštanj tap water
10
0,2
Spring Velenje
10
0,2
Spring Šoštanj
10
0,2
Velenje lake
10
0,2
River Homšnica
10
0,1
SAMPLE
• drinking water => NO3- = 25 mg/L (EC rules)
• drinking water => NO2- = max. 0,1 mg/L (EC rules)
NH4
+
 The presence of ammonium in water shows that the
water was in contact with rotting organic materials,
fecals..
Our results
SAMPLE
NH4+
School tap water
0,05
Rahtel tap water
0,2
Vuhred tap water
0,2
Šoštanj tap water
0,2
Spring Velenje
0,05
Spring Šoštanj
0,05
Velenje lake
0,2
River Homšnica
0,2
• drinking water => NH4+ = 0,05 mg/L (EC rules)
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
Our results
SAMPLE
Fe
School tap water
0,3
Rahtel tap water
0,6
Vuhred tap water
0,2
Šoštanj tap water
0,4
Spring Velenje
0,1
Spring Šoštanj
0,1
Velenje lake
0,3
River Homšnica
0,4
• drinking water => Fe = max. 2 mg/L
WATER IN SLOVENIA
 To conclude:
 all pH values of drinking water are according to EC rules
 all PO43- values meet EC rules
 NO2- and NO3
ground water that contains over 25 mg NO3- /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 NH4+ value
 all Fe values meet EC rules