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EEC Water Quality Standards for Drinking Water
The water supply authorities are obligated to provide water of the following quality;
Following the publication of the Water Supply (Water Quality) Regulations, water must comply with a wide variety of chemical parameters. The water must also conform to a strict and clearly defined definition of wholesomeness. The EC directive list 66 drinking water parameters which can be divided into six groups, which are as follows:
The following table shows these parameters in more detail:
Water quality requirements set by the EC directive (Gray, 1994)
Parameter |
Unit of measurement |
G value |
MAC |
UK PCV |
Colour |
mg/l Pt-Co |
1 |
20 |
20 |
Turbidity |
Formazin Turbidity units |
0.4 |
4 |
4 |
Odour |
Dilution number at 250C |
- |
3 |
3 |
Taste |
Dilution number at 250C |
- |
3 |
3 |
Temperature |
0 C |
12 |
25 |
25 |
Hydrogen ion conc. |
pH Min |
6.5 |
5.5 |
|
Max |
8.5 |
9.5 |
9.5 |
|
Conductivity |
uS/cm at 200C |
400 |
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Chloride |
mg Cl/l |
25 |
200 |
|
Sulphate |
mg SO4/l |
25 |
250 |
250 |
Silica |
mg SiO2/l |
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Calcium |
mg Ca/l |
100 |
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Magnesium |
mg Mg/l |
30 |
50 |
50 |
Sodium |
mg Na/l |
20 |
150 |
150 |
Potassium |
mg K/l |
10 |
12 |
12 |
Aluminium |
mg Al/l |
0.05 |
0.2 |
0.2 |
Total hardness |
mg CaCO3/l |
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Dry residuals |
mg/I |
1500 |
1500 |
1000 |
Dissolved oxygen |
(a) |
(a) |
(a) |
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Free carbon dioxide |
(b) |
(b) |
(b) |
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Parameters concerning SUEA |
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Nitrates |
mg NO3/l |
25 |
50 |
50 |
Nitrites |
mg NO2/l |
0.1 |
0.1 |
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Ammonium |
mg NH4/l |
0.5 |
0.5 |
0.5 |
Kjeldahl nitrogen |
mg N/l |
1 |
1 |
|
Oxidizability (permanganate value) |
mg O2/l |
2 |
5 |
5 |
TOC (total organic carbon) |
mg C/l |
(c) |
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Hydrogen sulphide |
m g S/l |
UO |
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mg/l dry residuals |
0.1 |
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Dissolved or emulsified hydrocarbons; mineral oils |
m g /l |
10 |
10 |
|
Phenols (excludes natural phenols which do not react with chlorine) |
m g C6H5OH/l |
0.5 |
0.5 |
|
Boron |
u g B/l |
1000 |
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Surfactants |
ug /l as lauryl sulphate |
200 |
200 |
|
Other organochlorine compounds not covered by parameter 55 |
m g /l |
1 |
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Iron |
ug Fe/l |
50 |
200 |
200 |
Manganese |
ug Mn/l |
20 |
50 |
50 |
Copper |
ug Cu/l |
100 (d) |
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3000 (e) |
3000 |
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Zinc |
ug Zn/l |
100 (d) |
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5000 (e) |
5000 |
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Phosphorus |
ug P2O5/l |
400 |
5000 |
2200 |
Fluoride |
ug F/l |
1500 |
1500 |
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Cobalt |
ug Co/l |
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Suspended solids |
mg /l |
0 |
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Residual chlorine |
mg Cl/l |
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Barium |
ug Ba/l |
100 |
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Silver |
ug Ag/l |
10 |
10 |
|
80 (f) |
80 (f) |
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Parameters concerning toxic substances |
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Arsenic |
ug As/l |
50 |
50 |
50 |
Beryllium |
ug Be/l |
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Cadmium |
ug Cd/l |
5 |
5 |
5 |
Cyanides |
ug CN/l |
50 |
50 |
50 |
Chromium |
ug Cr/l |
50 |
50 |
50 |
Mercury |
ug Hg/l |
1 |
1 |
1 |
Nickel |
ug Ni/l |
50 |
50 |
50 |
Lead |
ug Pb/l |
50 (g) |
50 |
50 |
Antimony |
ug Sb/l |
10 |
10 |
10 |
Selenium |
ug Se/l |
10 |
10 |
10 |
Vanadium |
ug V/l |
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Pesticides and related products |
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(i) individual subs |
ug /l |
0.1 |
0.1 |
0.1 |
(ii) total |
ug /l |
0.5 |
0.5 |
0.5 |
Polycyclic aromatic hydrocarbons |
ug /l |
0.2 |
0.2 |
0.2 |
Microbiological parameters |
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Total coliforms |
No./100ml |
0 |
0 |
|
Feacal coliforms |
No./100ml |
0 |
0 |
|
Faecal strep |
No./100ml |
0 |
0 |
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Sulphite-reducing clostridia |
No./20ml |
<1 |
<1 |
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Total bacterial colony counts |
No./ml at 220C |
10 |
NSI |
|
No./ml at 370C |
100 |
NSI |
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Total bacteria counts for water in enclosed containers |
No./ml at 370C |
5 |
20 |
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No./ml at 220C |
20 |
100 |
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Minimum required conc for softened water intended for human consumption |
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Total hardness |
mg CaCO3/l |
60 |
60 |
60 |
Hydrogen ion conc. |
pH |
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Alkalinity |
mg HCO3/l |
30 |
30 |
30 |
Dissolved oxygen |
mg O2/l |
- a-Saturation should be above 75% except for groundwater.
- b-Water should not be aggressive.
- c-No significant increase over that normally observed.
- d- At outlets of pumping and/or treatment works and their substations.
- e- After the water has been standing for 12 hours in the piping and at the point where the water is made available to the consumer
- f- If silver is used in the water treatment process (unusual).
- g- In running water. Where lead pipes are present the lead content should not exceed 50m g/l in a sample taken after flushing. If a sample is taken directly or after flushing and the lead content either frequently or to an appreciable extent exceeds 100 m g/l, suitable measures must be taken to reduce the exposure to lead on the part of the consumer.
