Drinking water must be ‘wholesome’ and this is defined in law by standards for a wide range of substances, organisms and properties of water in regulations.
The standards are set to be protective of public health and the definition of wholesome reflects the importance of ensuring that water quality is acceptable to consumers.
There is good agreement worldwide on the science behind the setting of health based standards for drinking water, and this expert evidence is documented by the World Health Organisation in the Guidelines for Drinking Water Quality.
The legal standards in the UK are explained fully in the Water Supply (Water Quality) Regulations 2016.
Below is a brief guide to the regulations and was correct at the time of publication. It is advisable to double check these standards with any amended version of the UK Government regulations above
National Requirements
| Parameters | Maximum Value | units of Measurement | point of compliance |
|---|---|---|---|
| Aluminium | 200 | µgAl/l | Consumers’ taps |
| Colour | 20 | mg/l Pt/Co | Consumers’ taps |
| Iron | 200 | µgFe/l | Consumers’ taps |
| Manganese | 50 | µgMn/l | Consumers’ taps |
| Odour | <1 at 25 °C | Dilution number | Consumers’ taps |
| Sodium | 200 | mgNa/l | Consumers’ taps |
| Taste | <1 at 25 °C | Dilution number | Consumers’ taps |
| Tetrachlormethane | 3 | µg/l | Consumers’ taps |
| Turbidity | 4 | NTU | Consumers’ taps |
CHEMICAL PARAMETERS
| Parameters | Maximum Value | units of Measurement | point of compliance |
|---|---|---|---|
| Acrylamide | 0.10 | µgA/l | (i) |
| Antimony | 5.0 | µgSb/l | Consumers’ taps |
| Arsenic | 10 | µgAs/l | Consumers’ taps |
| Benzene | 1.0 | µg/l | Consumers’ taps |
| Benso(a)pyrene | 0.010 | µg/l | Consumers’ taps |
| Boron | 1.0 | mgB/l | Consumers’ taps |
| Bromate | 10 | µgBrO3/l | Consumers’ taps |
| Cadmium | 5.0 | µgCd/l | Consumers’ taps |
| Chromium | 50 | µgCr/l | Consumers’ taps |
| Copper(ii) | 2.0 | mgCu/l | Consumers’ taps |
| Cyanide | 50 | µgCN/l | Consumers’ taps |
| 1,2 dichloroethane | 3.0 | µg/l | Consumers’ taps |
| Epichlorohydrin | 0.10 | µg/l | (i) |
| Fluoride | 1.5 | mgF/l | Consumers’ taps |
| Lead(ii) | 10 | µgPb/l | Consumers’ taps |
| Mercury | 1.0 | µgHg/l | Consumers’ taps |
| Nickel | 20 | µgNi/l | Consumers’ taps |
| Nitrate | 50 | mgNO3/l | Consumers’ taps |
| Nitrite | 0.50 | mgNO2/l | Consumers’ taps |
| 0.10 | Treatment works |
PESTICIDES
| Parameters | Maximum Value | units of Measurement | point of compliance |
|---|---|---|---|
| Aldrin | 0.030 | µg/l | Consumers’ taps |
| Dieldrin | 0.030 | µg/l | Consumers’ taps |
| Heptachlor | 0.030 | µg/l | Consumers’ taps |
| Heptachlorepoxide | 0.030 | µg/l | Consumers’ taps |
| Other Pesticides | 0.10 | µg/l | Consumers’ taps |
| Pesticides:Total | 0.50 | µg/l | Consumers’ taps |
| Polycyclic aromatic hydrocarbons | 0.10 | µg/l | Consumers’ taps |
| Selenium | 10 | µg/l | Consumers’ taps |
| Tetrachloroehtane | 10 | µg/l | Consumers’ taps |
| Trichloroethane | 10 | µg/l | Consumers’ taps |
| Trihalomethanes | 100 | µg/l | Consumers’ taps |
| Vinyl chloride | 0.50 | µg/l | Consumers’ taps |
MICROBIOLOGICAL PARAMETERS
| Parameters | Maximum Value | units of Measurement | point of compliance |
|---|---|---|---|
| Coliform bacteria | 0 | number/100ml | Treatment works |
| Enterococci | 0 | number/100ml | Consumers’ taps |
| Escherichia coli (E.coli) | 0 | number/100ml | Treatment works |
| Escherichia coli (E.coli) | 0 | number/100ml | Consumers’ taps |