Overview
EN ISO 4064-1:2025 (adoption of ISO 4064-1:2024) defines the metrological and technical requirements for water meters used to measure the volume of cold potable water and hot water in fully charged, closed conduits. Published by CEN, this standard covers mechanical, electrical/electronic and hybrid water meters that incorporate an indicating device for accumulated volume, and it also addresses electronic ancillary devices (optional unless mandated by national/regional regulation).
Key topics and technical requirements
- Scope and meter types: Applies to mechanical, electronic and combined principle water meters for potable and hot water in closed conduits; includes requirements for separate calculators and measurement transducers.
- Metrological characteristics: Defines the values and definitions for flow rates Q1, Q2, Q3 and Q4, accuracy classes, and maximum permissible error (MPE) across operating ranges.
- Specified MPE examples (from Annex ZA alignment with EU requirements):
- ±2% for flow between Q2 (included) and Q4 at water temperature ≤ 30 °C
- ±3% for flow between Q2 (included) and Q4 at water temperature > 30 °C
- ±5% for flow between Q1 and Q2 (excluded), for any temperature
- Operating and environmental conditions: Temperature classes, static/relative pressure limits, climatic and mechanical environments, electromagnetic immunity and resistance to other influences.
- Technical features: Requirements for indicating devices, calculators, correction and adjustment devices, connections between electronic parts, and security (hardware/software protection, prevention of reset of total quantity).
- Durability and conformity testing: Durability, repeatability, reproducibility, and post-durability error limits. Normative test methods are provided in related Part 2 (EN ISO 4064-2:2025 / ISO 4064-2:2024).
- Marking and information: Required inscriptions, units (cubic metre), display/readability requirements and documentation for operation and installation.
- Regulatory alignment: Annex ZA maps this standard to essential requirements of Directive 2014/32/EU (measuring instruments), supporting presumption of conformity when cited in the Official Journal.
Applications and users
- Utilities and municipal water supply systems selecting or specifying meters for billing and custody transfer
- Meter manufacturers designing or certifying mechanical, electromagnetic, ultrasonic or hybrid water meters and ancillary devices
- Test laboratories and conformity assessors applying metrological tests and durability evaluations (see Part 2 for test methods)
- Regulators and procurement teams ensuring compliance with EU measuring instrument requirements and national regulations
Related standards
- EN ISO 4064-2:2025 / ISO 4064-2:2024 - Water meters - Part 2: Test methods (normative reference)
- OIML R 49 series (referenced in ISO texts) for international metrological practice
EN ISO 4064-1:2025 is essential for anyone involved in the specification, manufacture, testing or regulatory compliance of water meters used in potable and hot water distribution.