What is Backflow?


Water fittings regulations require every plumbing system to incorporate protection against backflow. This is often referred to as point of use backflow protection. It can be provided by an air or tap gap arrangement or a mechanical backflow prevention device.

Backflow prevention devices, are required to be manufactured of gunmetal or other dezincification resistant materials.

Wherever practicable plumbing systems should be protected against backflow without the necessity to rely on mechanical backflow protection devices.


Fluid Categories


Regulations classify the health risk posed by potential contaminants using a scale called fluid categories.

There are five fluid categories in total the lowest being 1 no risk the highest 5 a serious health hazard.


Fluid Category




Wholesome (drinking) water supplied by the undertaker

water direct from a water undertaker’s main


Wholesome (drinking) water which has been changed either heated or altered in taste, odour or appearance

Hot water


Fluids posing a slight health hazard

low toxicity chemicals such as common disinfectants


Fluids posing a significant health hazard.

Toxic substances such as pesticides and environmental organisms


Fluids posing a serious health hazard

Pathogenic organisms, radioactive or very toxic substances such as faecal matter

Further guidance can be found on the WaterRegsUK website.



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