Water Supply Industry Interpretations and Advice

  • Area of Interest : Installation
  • Topic : Pressure testing
  • Title : BS EN 806: pressure testing requirements
  • Clause Reference : Schedule 2 paragraph 5 & G5.1
  • Reference Number : I35
  • Decision Date : October 2012

Pressure testing of pipework – recommendations made in BS EN 806

It has been suggested that BS EN 806 recommends that plumbing installations and fittings be pressure tested at 1.1 times the maximum working pressure rather than the 1.5 times required by the Water Supply (Water Fittings) Regulations, Byelaws in Scotland. 

Having reviewed all the relevant definitions and clauses given in BS EN 806 parts 1-5 WRAS believes that rather than advocating a lower pressure test than that required by the UK national requirements BS EN 806 actually recommends a slightly higher test pressure. With the result that should an installation be designed to satisfy the pressure test recommendations given in BS EN 806, then it will by default comply with those of the Water Fittings Regulations /Byelaws

Summary of requirements of BS EN 806:

BS EN 806: Part 1 defines maximum design pressure (MDP) of a system as:-
‘the maximum hydrostatic pressure at which the potable water installation is designed to work’

BS EN 806: Part 2 covers design, clause 3.4.2 which covers strength states:-
‘To ensure adequate strength, all components of the system shall be designed to meet the test pressure requirements of the local and national laws and regulations. The test pressure shall be at least 1.5 times the allowable maximum operating pressure (PMA).’

Therefore the maximum design pressure should be at least 1.5 times the maximum operating pressure.
MDP = 1.5 x maximum operating pressure

BS EN 806: Part 4 covers installation and commissioning, clauses 6.1.2 and 6.1.3 identifying the test procedure for commissioning plumbing installations, with the test pressure being specified as:-
1.1 x maximum design pressure (MDP)

So to satisfy the recommendations given in BS EN 806 a fitting must be pressure tested at:-
1.1 x (1.5 x maximum design pressure) or
1.65 x maximum operating pressure

This results in a slightly higher testing requirement than the statutory minimum required by Water Fittings Regulations and Scottish Water Byelaws in Schedule 2 Paragraph 5 which is at least 1.5 times the maximum working or operating pressure which the installation will be subjected to.

Example
If a system is designed to operate at a maximum working pressure of 5 bar:
Regulatory requirement as set out in the Water Fittings Regulations/Byelaws require the system to be pressure tested at:-
1½ x 5 bar =7.5 bar
BS EN 806 recommends a test pressure of:-
1.1 x maximum design pressure (MDP)
where
MDP = 1½ x maximum operating pressure
1.1 x [1½ x 5 bar] = 8.25 bar