Water Supply Industry Interpretations and Advice

  • Area of Interest : Installation
  • Topic : Supply pressure
  • Title : Maximum and minimum supply pressure
  • Clause Reference : Regulation 4 (1) (b)
  • Reference Number : I22
  • Decision Date : May 2009

There is no legal requirement in respect of maximum supply pressure. Where the supply pressure exceeds the maximum working pressure of fittings it is the customer’s responsibility to install a suitable pressure reducing valve or change the fittings for ones suitable for the existing supply pressure.

The minimum pressure requirements as set out in the Water industry Act (1991), Water (Scotland) Act 1980 and Water and Sewerage Services (Northern Ireland) Order 2006, is that needed to supply the top-most storey of every building within the undertaker's area of supply. However the water supplier is not required to deliver water at a height greater than that to which it will flow by gravitation through the existing water mains from the service reservoir or tank from which the supply is taken.

A supply capable of delivering 9 litres/minute at a pressure of 10m head at the boundary of the property is an Ofwat reporting criterion.