Regulations
If a private water supply is to be used as a source of drinking water, it is essential that it complies with The Private Water Supply Regulations for water which is intended for human consumption. Your local authority may insist on testing your supply. The Regulations define a number of “Prescribed Concentrations or Values” (PCVs) relating to a range of chemical and bacteriological parameters.
Drinking Water Standards
Prescribed concentrations or values (maximum unless otherwise stated).
The Water Supply (Water Quality) Regulations 2016
Parameter | Unit | Concentration or value |
Acrylamide | µg/litre | 0.10 |
Aluminium | µg Al/litre | 200 |
Ammonium | mg NH4/litre | 0.5 |
Antimony | µg Sb/litre | 5 |
Arsenic | µg As/litre | 10 |
Benzene | µg/litre | 1.0 |
Benzo(a)pyrene | µg/litre | 0.010 |
Boron | mg B/litre | 1.0 |
Bromate | µgBrO3/litre | 10 |
Cadmium | µg Cd/litre | 5 |
Chloride | mg Cl/litre | 250 |
Chromium | µg Cr/litre | 50 |
Coliforms (faecal) | number/100ml | 0 |
Coliforms (total) | number/100ml | 0 |
Colony Counts | number/ml | no significant increase |
Colour (filtered) | mg/litre Pt scale | 20 |
Conductivity | µS/cm | 2500 @ 20°C |
Copper | mg/Cu/litre | 2.0 |
Cyanide | µgCN/litre | 50 |
1, 2 dichloroethane | µg/litre | 3.0 |
Epichlorohydrin | µg/litre | 0.10 |
Faecal streptococci | number/100ml | 0 |
Fluoride | mg F/litre | 1.5 |
Iron | µg Fe/litre | 200 |
Lead | µg Pb/litre | 10 |
Manganese | µg Mn/litre | 50 |
Mercury | µg Hg/litre | 1 |
Nickel | µg Ni/litre | 20 |
Nitrate | mg NO3/litre | 50 |
Nitrite | mg NO2/litre | 0.5 |
Odour | dilution number | 3 @ 25°C |
PAH (Polycyclic Aromatic Hydrocarbons) | µg/litre | 0.1 |
Pesticides (total) | µg/litre | 0.5 |
pH | pH value | 6.5 (min) – 10.0 (max) |
Selenium | µg Se/litre | 10 |
Sodium | mg Na/litre | 200 |
Sulphate | mg SO4/litre | 250 |
Sulphite reducing clostridia | number/100ml | 0 |
Taste | dilution number | 3 @ 25°c |
Tetrachloroethene/Trichloroethene | µg/litre | 10 |
Tetrachloromethane | µg/litre | 3 |
TOC (Total Organic Carbon) | mg C/litre | no significant increase |
Trihalomethanes | µg/litre | 100 |
Tritium (for radioactivity) | Bq/litre | 100 |
Turbidity | NTU | 4 |
Vinyl Chloride | µg/litre | 0.5 |

