Zone and/or whole-site backflow protection might be required at marinas, ports and harbours for a number of reasons including:

  • as an interim measure, until full compliance with the Byelaws for point of use backflow protection is obtained
  • where there has been compliance for point of use, but there is a risk that future modification to the system and/or inadequate control of the water system might compromise compliance

And in ports and harbours:

  • where there is compliance for point of use backflow protection, but additional security is required because there remains a concern that in the event of backflow, the risk to public health would be significant. 

The decision to permit installation of a temporary device, and the level of protection required to be offered by that device, is at the discretion of the Water Authority and depends on the risk assessment for the installation. Further details and advice are given in the WRAS Information and Guidance Note 9-04-5,'Report of the Expert Group on the Risk of Contamination of the Public Water Supply by Backflow'.