Quality & Inspections · Mandatory · Construction

Pressure Test Record

A record of pressure testing on pipework systems including heating, gas, and water installations.

Last reviewed: 29 March 2026 — This guide reflects UK law as of this date. BS EN 806 / Gas Safety Regs remains current with no amendments enacted as of 29 March 2026. Next scheduled review: 29 March 2027.

Legal basis	BS EN 806 (water systems) + Gas Safety (Installation and Use) Regulations 1998 (gas systems) + WRAS (Water Regulations Advisory Scheme)
Why pressure test	Verifies leak-tight integrity before insulation, burial, or commissioning — the last opportunity to detect defects while joints remain accessible
Water systems	Test at 1.5× maximum working pressure, hold for a minimum of 1 hour, no pressure drop acceptable
Gas systems	Tightness testing is mandatory before any appliance connection — must be carried out by a Gas Safe registered engineer only
WRAS	All fittings in contact with drinking water must be WRAS approved to confirm no contamination of the wholesome supply

1. Pressure Testing — The Last Chance to Find Leaks Before Concealment

The pressure test is the quality gate between pipework installation and concealment or commissioning. It is the definitive confirmation that every joint, fitting, and length of pipework is leak-tight at a pressure above normal service conditions. Once pipework is insulated, buried, or enclosed in walls, floors, or ceilings, finding and repairing a leak becomes enormously disruptive and costly.

For water systems, testing is governed by BS EN 806 and the Water Supply (Water Fittings) Regulations. The test pressure is typically 1.5 times the maximum working pressure, held for a minimum of one hour with no measurable pressure drop. For gas systems, tightness testing is a mandatory requirement under the Gas Safety (Installation and Use) Regulations 1998 and must be performed by a Gas Safe registered engineer in accordance with IGEM/UP/1C. The test method, medium, and acceptance criteria differ between water and gas — and the consequences of failure in either case can be severe.

The pressure test record captures every detail of the test: the system tested, the test medium, the pressures applied, the hold period, visual inspection findings, and the identity of the tester and witness. Without a complete and signed record, there is no evidence that the test was carried out correctly — or at all.

Never conceal untested pipework

Never conceal pipework that has not been pressure tested and signed off — finding leaks after concealment is enormously costly. Insulation, plasterboard, screed, and backfill must not proceed until the test record is complete.

2. Pressure Test Record Fields

The following table sets out the fields that must be captured on a pressure test record. Each field serves a specific purpose in demonstrating that the test was correctly planned, executed, and witnessed.

Field	Description
Project/system	Identifies the project and the specific system or section under test
Date	Date of the pressure test
System type	Domestic cold water, hot water, LTHW heating, gas, CHW, fire suppression, etc.
Test medium	Water, air, or inert gas — must match specification and standard requirements
Working pressure	Maximum normal operating pressure of the system (bar)
Test pressure	Pressure applied during the test — typically 1.5× working pressure for water systems
Pressure source	Manual pump, electric pump, or mains supply used to pressurise the system
Pre-test checks	Air purged, system filled, sensitive instruments isolated, all joints accessible
Test start	Time and pressure reading at the start of the hold period
Hold period	Duration of the hold period — minimum 1 hour for water systems
Pressure at end	Pressure reading at the end of the hold period
Visual inspection	Confirmation that all accessible joints were visually inspected during and after the hold
Result	Pass or fail, with comments on any anomalies observed
Tested by	Name, signature, and qualifications of the person who conducted the test
Witnessed by	Name and signature of the witness (client representative, clerk of works, or engineer)

3. Common Mistakes

Concealing pipework before testing

Insulation, plasterboard, screed, or backfill applied before the pressure test has been completed and signed off. Once concealed, any leak requires destructive investigation to locate and repair — at significant cost and programme delay.

Air testing where water testing is required

Some specifications and standards require hydraulic (water) testing, not pneumatic (air) testing. Air testing of certain systems may not detect small leaks that a hydraulic test would reveal. Always check the applicable standard and specification before selecting the test medium.

Using an uncalibrated gauge

A pressure gauge that has not been calibrated within its certification period renders the test result unverifiable. Calibration certificates must be current and retained alongside the test record as evidence of gauge accuracy.

Not isolating sensitive instruments before pressurising

Pressure relief valves, expansion vessels, and sensitive instrumentation must be isolated before the system is pressurised to test pressure. Failure to isolate can damage components rated for normal operating pressure only.

Gas testing by a non-Gas Safe registered person

All gas tightness testing must be carried out by a Gas Safe registered engineer. It is a criminal offence for an unregistered person to carry out any gas work, including tightness testing. The test record must include the engineer's Gas Safe registration number.

4. Frequently Asked Questions

What is the test pressure for domestic cold water systems?▾

1.5 times the maximum operating pressure. For a typical domestic cold water system operating at 3 bar, the test pressure is 4.5 bar. The test must be held for a minimum of one hour with no measurable pressure drop.

Can plastic pipework systems be air tested?▾

Some plastic pipework systems can be air tested, but only where the manufacturer's instructions and the applicable standard permit it, and a suitable risk assessment has been carried out. Air testing carries additional risks because air is compressible — a failure under air pressure releases energy more violently than a failure under water pressure.

What does WRAS approval mean?▾

WRAS (Water Regulations Advisory Scheme) approval confirms that a product or fitting has been tested and found to comply with the Water Supply (Water Fittings) Regulations. It provides assurance that the product will not contaminate drinking water through leaching, taste, odour, or microbial growth.

What records must a Gas Safe engineer provide after gas work?▾

A Gas Safe registered engineer must provide a Gas Safety Record (tightness test confirmation), a Tightness Test Record (documenting the test method and result), and a Commissioning Record for each gas appliance installed. These records must be provided to the client and retained by the installing company.

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