ISO 15875-1:2025

Overview - ISO 15875-1:2025 (PE‑X piping systems, General)

ISO 15875-1:2025 establishes the general requirements for plastics piping systems made from crosslinked polyethylene (PE‑X) intended for hot and cold water installations inside buildings - including domestic potable water and heating systems. Part 1 sets the scope, terminology and the basis for test parameters used across the ISO 15875 series and defines service conditions, application classes and pipe dimension considerations. It is a foundational document to be used together with the other parts of the ISO 15875 series.

Key topics and technical requirements

• Scope and application: systems for conveyance of water within buildings, whether or not intended for human consumption, and heating systems; covers a range of application classes and pipe dimension classes.
• Terminology and symbols: definitions for “piping system”, nominal size (DN/OD), nominal outside diameter, mean outside diameter, pipe series (S) and calculated pipe values - ensuring consistent design and communication.
• Service conditions: classification of application classes (linked to a 50‑year design period), design pressure options (e.g., 4, 6, 8 and/or 10 bar) and definitions for design temperature (TD), maximum temperature (Tmax) and malfunction temperature (Tmal) (note: the standard excludes values outside those listed in Table 1).
• Testing framework: basis for test parameters referenced in ISO 15875‑2/‑3/‑5; restrictions on test result interchangeability and the warning that system test results cannot be transferred between different pipe/fitting combinations.
• Material aspects: general material requirements, influence on water quality for human consumption, reaction to fire, and guidance on the use of reworked material and recyclate.
• Technical product information: requirements for documentation and information supplied with PE‑X products.

Practical applications - who uses this standard

ISO 15875-1 is intended for:

• Manufacturers of PE‑X pipes, fittings and components (to align product design and testing).
• System designers and consulting engineers specifying piping for domestic, sanitary and heating installations.
• Installers and contractors who need to understand system classes, pressures and jointing compatibility.
• Testing laboratories and conformity assessors applying the ISO 15875 test methods.
• Regulators and specifiers setting procurement and safety requirements.

Use cases include specifying PE‑X systems for residential plumbing, commercial building water supply and hydronic heating, ensuring material compatibility, and defining testing and documentation for certification.

Related standards

• ISO 15875 series: ISO 15875‑2 (Pipes), ISO 15875‑3 (Fittings), ISO 15875‑5 (Fitness for purpose), ISO/TS 15875‑7 (Conformity guidance)
• Other piping material series referenced: ISO 15874, ISO 15876, ISO 15877, ISO 21003, ISO 22391

Keywords: ISO 15875-1:2025, PE‑X, crosslinked polyethylene, plastics piping systems, hot and cold water installations, application classes, design pressure, pipe dimension classes, test methods.