Guideline values

There are a range of guidelines and regulations for drinking water quality operating at a worldwide down to country level. Below, we have collated values from The Private Water Supplies Regulations (England, Scotland and Wales), The European Union Drinking Water Directive and The World Health Organisation into an easily comparable table. 

Parameter

Unit of measurement

Standards for private water supplies in england (2016)

Standards for Private Water Supplies in Scotland (2006)

Standards for Private Water Supplies in Wales (2017)

World Health Organisation Standards (1993)

European Union Drinking Water Directive (1998)

Parameter

Unit of measurement

Standards for private water supplies in england (2016)

Standards for Private Water Supplies in Scotland (2006)

Standards for Private Water Supplies in Wales (2017)

World Health Organisation Standards (1993)

European Union Drinking Water Directive (1998)

Aesthetic parameters
Colour mg/l Pt/Co 20 20 20 Acceptable to the consumer Not mentioned
Odour Dilution number Acceptable to consumers and no abnormal change 3 at 25ºC Acceptable to consumers and no abnormal change Acceptable to the consumer Not mentioned
Taste Dilution number Acceptable to consumers and no abnormal change 3 at 25ºC Acceptable to consumers and no abnormal change Acceptable to the consumer Not mentioned
Turbidity NTU (Nephelometric Turbidity Unit) 4 4 4 Acceptable to the consumer Not mentioned
Microbiological parameters
Coliforms number/ 100ml 0 0 0 Not mentioned 0
Colony Count at 22°C number or cfu/ml 100 (water in bottles or containers) No abnormal change No abnormal change Not mentioned 100
Colony Count at 37°C number or cfu/ml 20 (water in bottles or containers) Not mentioned Not mentioned Not mentioned 20
Clostridium number/ 100ml 0 0 0 Not mentioned 0
E.Coli number/ 100ml 0 0 0 Not mentioned 0
Enterococci number/ 100ml 0 0 0 Not mentioned 0
Pseudonoma number/ 250ml 0 0 0 Not mentioned 0
Chemical parameters
Acrylamide μg/l 0.10 0.10 0.10 Not mentioned 0.10
Aluminium μg/l 200 200 200 200 200
Ammonia mg/l Not mentioned Not mentioned Not mentioned Not mentioned 0.50
Ammonium mg/l 0.50 0.50 0.50 Not mentioned Not mentioned
Antimony μg/l 5.0 5.0 5.0 5.0 5.0
Arsenic μg/l 10 10 10 10 10
Benzene μg/l 1.0 1.0 1.0 Not mentioned 1.0
Benzo(a)pyrene μg/l 0.010 0.010 0.010 Not mentioned 0.010
Boron mg/l 1.0 1.0 1.0 0.3 1.0
Bromate μg/l 10 10 10 Not mentioned 10
Cadmium μg/l 5.0 5.0 5.0 3.0 5.0
Calcium mg/l Not mentioned Not mentioned Not mentioned No guideline No guideline
Chloride mg/l 250 250 250 250 250
Chromium μg/l 50 50 50 50 50
Conductivity μS/ cm at 20°C 2500 2500 2500 2500 2500
Copper mg/l 2.0 2.0 2.0 2.0 2.0
Cyanide μg/l 50 50 50 70 50
1,2 dicloroethane μg/l 3.0 3.0 3.0 Not mentioned 3.0
Epichlorohydrin μg/l 0.10 0.10 0.10 Not mentioned 0.10
Fluoride mg/l 1.5 1.5 1.5 1.5 1.5
Hydrogen ion (pH) pH Value 6.5 minimum to 9.5 maximum 6.5 minimum to 9.5 maximum 6.5 minimum to 9.5 maximum No guideline Not mentioned
Iron μg/l 200 200 200 No guideline 200
Lead μg/l 10 10 10 10 10
Manganese μg/l 50 50 50 500 500
Magnesium mg/l Not mentioned Not mentioned Not mentioned No guideline No guideline
Mercury μg/l 1.0 1.0 1.0 1.0 1.0
Nickel μg/l 20 20 20 20 20
Nitrate mg/l 50 50 50 50 50
Nitrite mg/l 0.50 0.50 0.50 3 (as nitrite ion) 0.50
Polycyclic aromatic hydrocarbons (PAHs) μg/l 0.10 0.10 0.10 Not mentioned 0.10
Selenium μg/l 10 10 10 10 10
Silver μg/l Not mentioned 10 Not mentioned No guideline Not mentioned
Sodium mg/l 200 200 200 200 200
Sulphate mg/l 250 250 250 500 250
Tetrachloroethene and trichloroethene μg/l 10 10 10 Not mentioned 10
Trihalomethanes: Total μg/l 100 100 100 Not mentioned 100
Total dissolved solids (TDS) mg/l Not mentioned Not mentioned Not mentioned No guideline Not mentioned
Total organic carbon (TOCs) mg/l No abnormal change No abnormal change No abnormal change Not mentioned No abnormal change
Vinyl Chloride μg/l 0.50 0.50 0.50 Not mentioned 0.50
Zinc μg/l Not mentioned 5000 Not mentioned 3000 Not mentioned
Pesticides
Aldrin μg/l 0.030 0.030 0.030 0.030 0.030
Dieldrin μg/l 0.030 0.030 0.030 0.030 0.030
Heptachlor μg/l 0.030 0.030 0.030 No guideline 0.030
Heptachlor epoxide μg/l 0.030 0.030 0.030 No guideline 0.030
Other pesticides μg/l 0.10 0.10 0.10 Not mentioned 0.10
Pesticides total μg/l 0.50 0.50 0.50 Not mentioned 0.50
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