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Understanding Backflow Regulations and What They Mean When Boosting Water Performance

What is Backflow?

Backflow refers to the undesirable reversal of water flow within a plumbing system, the main cause being back siphonage or back pressure. This reversal can, in certain scenarios, allow contaminated water or substances to flow back into the mains water supply, posing risks to public health and safety.

What are the Backflow Regulations?

The Water Supply Regulations (1999) have identified five categories; each of which represent varying levels of health hazards:

  • CAT 1: Drinking water; complying with the requirements of regulations made under section 67 of the Water Industry Act 1991[1]
  • CAT 2: Water in CAT 1 with aesthetic changes in taste, odour, or appearance.
  • CAT 3: Water with a slight health hazard, which may contain low toxicity such as common disinfectants
  • CAT 4: Water with a significant health hazard which includes pesticides or environmental organisms
  • CAT 5: Water with a serious health hazard which includes very toxic substances, faecal or other human/animal waste

Backflow protection plays a critical role in keeping drinking water in a mains-fed system safe. It acts as a one-way valve in your plumbing system, ensuring that water only flows in one direction.

Appropriate backflow prevention measures must be implemented, especially for category 5 water supply, as per the Water Supply Regulations (1999).   An appliance with a fluid category 4 backflow risk must also have a backflow prevention device or arrangement of fittings. There are different backflow prevention arrangements and devices for different fluid categories on the Water Regs UK website.

How Does This Impact Me When Looking to Boost Water Pressure and Flow?

You should consider using a water tank with backflow protection when there’s a risk of CAT 5 contaminated water flowing back into the clean water supply. TankBoost CAT 5 is suitable for boosting water pressure and flow in these scenarios.

TankBoost CAT 5 will boost water pressure up to 3.0 bar and flow up to 80 litres per minute in a mains fed system, designed to boost multiple outlets at once. The product features a type AB air gap between the inlet and outlet to ensure that the water in the tank or cistern does not flow back into the mains water supply.

TankBoost CAT5 features AB air gap diagram

CAT 5 water tanks are suitable for commercial or industrial properties which may include laboratories, chemical cleaners, healthcare premises, abattoirs and animal grooming parlours. These carry the highest risk level of the most serious health hazard because of the presence of raw sewage or hazardous waste.


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