Installation: FAQs

Is the pressure testing specified in BS EN 806 acceptable?


The pressure testing requirements specified in BS EN 806 recommends that plumbing installations and fittings be 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.

However due to the terms and definitions applied 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

To comply with the requirements of schedule 2 paragraph 15 (1) a backflow prevention device or arrangement rated to at least fluid category 2 must be installed 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)


MDP = 1½ x maximum operating pressure
1.1 x [1½ x 5 bar] = 8.25 bar



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