This document specifies: " general requirements for water supply systems outside buildings including potable water mains and service pipes, service reservoirs, other facilities and raw water mains but excluding treatment works and water resources development; " general requirements for components; " general requirements for inclusion in product standards which can include specifications which are more stringent; " requirements for installation, site testing and commissioning. The requirements of this document apply to: " the design and construction of new water supply systems; " the extension of significant areas forming a coherent part of an existing water supply system; " interconnections between water supply systems; " significant modification and/or rehabilitation of existing water supply systems. NOTE It is not intended that existing water supply systems are altered to comply with this document, provided that there are no significant detrimental effects on water quantity, security, reliability and adequacy of the supply. However, this document is intended to cover all water infrastructure systems mentioned above since they are key to meet the sustainable goals of the cities and to show the urgent need to invest in them in order to consider fundamental aspects, such as resilience or mitigation/adaptation to climate change.