Overview
EN ISO 21003-5:2008 - "Multilayer piping systems for hot and cold water installations inside buildings - Part 5: Fitness for purpose of the system" is a CEN-endorsed ISO product standard that defines the fitness for purpose requirements and test parameters for multilayer piping systems used in domestic and heating water installations. It applies to multilayer pipes, fittings and their joints, including joints that contain other plastics or non-plastic components, and is intended to be used together with the other parts of ISO 21003 (Parts 1, 2, 3 and 7).
Key Topics
- Scope and applicability to building hot and cold water systems, including water for human consumption and heating circuits, under specified design pressures and temperatures (see ISO 21003-1 for application classes).
- Fitness for purpose criteria for joints and the overall piping system, specifying required behaviour rather than prescribing product construction.
- Defined test methods and parameters (clauses 5.2–5.7) that set the acceptable performance levels when using referenced standards.
- Required tests include:
- Internal pressure test (ISO 1167 series) - verifies leak-free performance under hydrostatic loading.
- Bending test (EN 713) - assesses leaktightness of assemblies when bent.
- Pull-out test (EN 712) - checks joint retention under axial load.
- Thermal cycling test (EN 12293) - evaluates performance under repeated temperature changes.
- Pressure cycling test (EN 12295) - assesses joint durability under fluctuating pressures.
- Vacuum leaktightness test (EN 12294).
- Clarifies that limits for Tmax, TD and Tmal follow ISO 21003-1 and that polymers used for stress-bearing layers include PB, PE-RT, PE-X, PP and PVC-C.
Applications
- Use for specifying and verifying multilayer piping systems in:
- Domestic cold and hot water distribution
- Building heating systems (radiators, underfloor heating when applicable)
- Useful when assessing system-level performance (not just individual components) prior to market release, conformity assessment, or design specification.
Who should use this standard
- Manufacturers of multilayer pipes, fittings and jointing systems
- Product designers and R&D engineers developing piping systems
- Test laboratories performing system performance verification
- Specifiers, consulting engineers, building services designers and compliance officers
- Regulatory authorities and conformity assessment bodies
Related standards
- ISO 21003-1, -2, -3, -7 (system general, pipes, fittings, conformity guidance)
- ISO 1167 series (internal pressure testing)
- ISO 17456 (long-term strength of multilayer pipes)
- ISO 15875-5, ISO 15876-5, ISO 15877-5, ISO 22391-5 (fitness-for-purpose parts for specific polymers)
- EN 712, EN 713, EN 12293, EN 12294, EN 12295 (joint and assembly test methods)
This standard is essential when specifying reliable, tested multilayer piping systems for building water services and for demonstrating system-level compliance through standardized testing.