Classifying contamination

The Water Regulations classify potential contaminants into 5 distinct categories based on the expected effects on the health of people who may come into contact with them. These are then applied to types of premises and fittings where they are likely to enter the public water supply.

A brief description of these 5 classifications is as follows:-

Fluid Category 1
This is wholesome water as supplied by the water company and complying to the requirements of section 67 of the Water Industry Act 1991 and the appropriate Water Supply (Water Quality) Regulations.

Fluid Category 2
Water essentially complying with the requirements for fluid category 1, but which has impaired aesthetic quality due to changes in temperature, taste, odour or appearance, such as a hot drink.

Fluid Category 3
Water which represents a slight health hazard because of the concentrations of substances of low toxicity, such as fertilizers sprays used in gardens.

Fluid Category 4
Any fluid which represents a significant health hazard due to the concentration of toxic substances or environmental organisms, such as the Legionella bacterium.

Fluid Category 5
Fluid representing a serious health hazard because of the concentration of pathogenic organisms, radioactive or toxic substances, such as faecal matter or blood.

For further examples of substances, and examples of vulnerable fittings in each of the above categories, please see Table 6.1 of the guidance to Schedule 2 of the Water Regulations, which can be found by following the link below.
www.defra.gov.uk