Water Supply Industry Interpretations and Advice

  • Area of Interest : Installation
  • Topic : Dead leg
  • Title : Dead legs
  • Clause Reference : Regulation 3 (2) (i)
  • Reference Number : I21
  • Decision Date : September 2008

Where water is allowed to stagnate there is a risk of contamination. Minimising this risk can be achieved by:

  • Completely removing redundant pipe work. Where this is not practicable the pipe should be terminated so that any ‘dead leg’ so created is no longer than twice the diameter of the pipe.
  • This general principle should also be applied to fittings which by design incorporate areas which do not have a steady through flow of water.
  • For pipework supplying fittings which are used infrequently i.e. fire supplies or water reuse systems with a back-up supply, appropriate backflow protection should be installed as close as reasonably practicable to the mains or supply/distributing pipe.