The efforts to establish consistent specifications for water meters on European and international level have lead to a revision of the series EN 14154 "Water meters", ISO 4064 "Measurement of water flow in fully charged closed conduits - Meters for cold potable water and hot water" and OIML R 49 "Water meters intended for the metering of cold potable water and hot water". The results are summarised in the framework of the EN ISO 4064 standard series, "Water meters for cold potable water and hot water". This consists of the following parts: - Part 1: "Metrological and technical requirements"; - Part 2: "Test methods"; - Part 3: "Test report format"; Part 4: "Non-metrological requirements not covered in ISO 4064-1"; Part 5: "Installation requirements". For this purpose, Part 4 specifies technical characteristics and particularly the dimensions for meters for cold potable water and hot water. The European Standard has been prepared by a Joint Working Group of ISO/TC 30/SC 7 "Volume methods including water meters" (secretariat: BSI, United Kingdom) and OIML TC 8/SC 5 "Water meters" (secretariat: BSI, United Kingdom) in collaboration with CEN/TC 92 (secretariat: SNV, Switzerland). The responsible German committee is NA 119-04-08 AA "Wasserzähler" ("Water meters") of the Water Practice Standards Committee (NAW).