ISO 4064-2:2005 specifies criteria for the selection of single, combination and concentric water meters, associated fittings, installation, special requirements for meters and the first operation of new or repaired meters to ensure accurate constant measurement and reliable reading of the meter. ISO 4064-2:2005 also applies to water meters, based on electrical or electronic principles and to water meters based on mechanical principles incorporating electronic devices, used to meter the actual volume flow of cold potable water. It also applies to electronic ancillary devices. The recommendations of this ISO 4064-2:2005 apply to water meters, irrespective of technology, defined as integrating measuring instruments continuously determining the volume of water flowing through them.