As defined in regulation 1, a category of fluid as described in schedule 1.

Schedule 1:

Fluid Category 1

Wholesome water supplied by the undertaker and complying with the requirements made under section 67 of the Water industry Act 1991/ the Water Supply (Water Quality) (Scotland) Regulations 1990 and any amendment

Fluid Category 2

Water in fluid category 1 whose aesthetic quality is impaired owing to:

• a change in its temperature, or
• the presence of substances or organisms causing a change in its taste, odour or appearance, including water in hot water distribution systems.

Fluid Category 3 

Fluid which represents a slight health hazard because of the concentration of substances of low toxicity, including any fluid which contains:

• ethylene glycol, copper sulphate solution or similar chemical additives, or

• sodium hypochlorite (chloros and common disinfectants)

Fluid category 4 

Fluid which represents a significant health hazard because of the concentration of toxic substances, including any fluid which contains:

• chemical, carcinogenic substances or pesticides (including insecticides an herbicides), or  
• Environmental organisms of potential health significance

Fluid Category 5

Fluid which represents a serious health hazard because of the concentration of pathogenic organisms, radioactive or very toxic substances, including any fluid which contains:

• faecal material or other human waste:
• butchery or other animal waste: or
• pathogens from any other source.