Introduction

BS EN 805 requires that every pipeline shall undergo a water pressure test prior to going into service to demonstrate the leaktightness of the installed system. This can be achieved by pressurising the constructed pipeline under controlled conditions to correctly specified test parameters and pass/fail criteria.

It is essential that every water supply pipeline and sewer rising main is tested, but hydrostatic pressure testing is a hazardous activity. It is the responsibility of all parties involved to ensure that this is carried out in a safe manner through assessment and management of risks, the application of safe systems of work and compliance with national legislation, regulation and guidance.

BS EN 805: 2025 permits the designer to specify a test procedure for pipes with viscoelastic behaviour.

This document specifies the UK test procedure for hydrostatic pressure testing of above and below ground pressure pipelines constructed from polyethylene or polyethylene barrier pipes.

It is intended this document will replace WIS 4-01-03 Issue 1: March 2024 and WIS 4-01-03A Issue 1 Amendment 1 October 2024 which will be archived (withdrawn) upon its publication.

This draft version the new WIS includes aspects / levels of detail not previously addressed. These include:

• testing of above ground pipelines;
• separation of test regimes for large and small diameter water supply pipelines;
• testing of pipelines above 180mm diameter
• testing of pipelines up to and including 180mm diameter
• testing of replacement pipelines
• more comprehensive testing of communication pipes forming part of service connections
• specific consideration of test pressures on valves and fittings
• an explanation of the nature of viscoelastic behaviour of PE and PE barrier pipelines

It also includes a requirement for the training and certification of organisations and individuals before they can undertake hydrostatic testing of PE and PE barrier pipelines.

An online calculator accompanies the draft WIS to assist users in understanding and complying with a number of the requirements of the Specification. Alternatively, equations are also provided for those who wish to work from first principles and/or understand the calculator’s functionality.

Note 1: It is intended that a replacement for IGN 4-01-03: 2015 (in the form of a WIS) will be created to address the requirements for hydrostatic pressure testing of all water supply pipelines (both viscoelastic and non-viscoelastic). It is further intended that that document will delegate the detail of hydrostatic pressure testing PE and PE barrier pipe to this WIS (i.e. WIS 4-01-03 Issue 2).

Note 2: For pipes of non-viscoelastic materials such as iron, steel, concrete and glass-reinforced polyester (GRP), the water loss method for hydrostatic pressure testing given in Section 10.4 of BS EN 805: 2025 applies. The water loss method is also advised by manufacturers of PVC-O pipes.

This document and the accompanying calculator have been prepared over 19 months by a Task & Finish Group on behalf of the Water UK Standards Board. The Group includes representatives from 18 organisations include English, Scottish and Irish water undertakers, the British Plastics Federation Pipes Group, a pipe supplier, a pipe testing laboratory, pipe testing training organisations, pipe test equipment manufacturers, pipe testing contractors, a valve manufacturer, independent consultants and Water UK. The Group will update the draft WIS as necessary based on comments received during the 3-month public commenting phase on the draft initiated here.

Information contained in this specification is given in good faith. Water UK cannot accept any responsibility for actions taken by others as a result.