This document specifies and gives guidance on: - general requirements for storage of water outside consumers' buildings, including service reservoirs for potable water and reservoirs containing water not for human consumption at intake works or within treatment works, excluding those that are part of the treatment process; - design; - general requirements for product standards; - requirements for quality control and auditing, testing and commissioning; - operational requirements; - requirements for inspection, rehabilitation and repair. The requirements of this document are applicable to: - design and construction of new reservoirs; - extension and modification of existing reservoirs; - significant rehabilitation of existing reservoirs. This document does not apply to reservoirs formed by the building of dams or the use of lakes for water storage purposes.