Specific installation advice


Heat energy recovery/exchange systems

Protecting public health

Minimising the risk of contaminated fluids coming into contact with water to be used for domestic purposes is a key objective of the water fittings regulations/byelaws. In keeping with this principle, where there is considered to be a contamination risk this is either mitigated by avoidance or safeguards such as installing backflow protection.



Depending upon their design and fluids involved, heating and cooling systems which make use of heat recovery or exchange, including but not limited to those listed below, pose different potential contamination risks.

  • Heat exchangers linking primary and secondary systems
  • Ground source and air source heat pumps
  • Chillers
  • Calorifiers
  • Heat recovery products utilising the heat energy in wastewater

In enforcing the regulations/byelaws water undertakers take a risk based and proportionate approach. Enforcement policies cite the need to be transparent, consistent, targeted and accountable.

Mindful of the need to ensure sufficient safeguards are in place to address the possibility of drinking water supplies coming into contact with fluids which are not considered to be wholesome, in determining whether water fittings/systems making use of heat recovery or exchange are compliant with regulation 4(1) the following factors will be taken into consideration. Please note decisions will be taken on a case by case basis.

  • The actual fluid categories of the fluids within the system.
  • How readily identifiable any potential integrity failure of the water fitting/system would be.
  • Whether the fitting design meets the requirements for single or double wall separation specified in BS EN 1717.


Please note: pipework supplying water for domestic use should be external to and separate from wastewater pipework. It should not be sealed within a fitting which conveys wastewater unless the local water undertaker has been notified and given consent.



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Uncontrolled if downloaded. This is informative, non-statutory guidance and intended for general guidance purposes only; it is subject to change.

Compliance with this information should not be relied upon as guaranteeing no enforcement action will be taken by water undertakers. Water Regs UK accepts no liability for loss, indirect or consequential loss arising from or in connection with this guidance document.