This British Standard specifies requirements for the materials, physical properties and performance of cold water storage cisterns and combined feed and expansion cisterns of up to 500 l capacity, from which water is drawn for domestic purposes. It also specifies requirements for the associated fittings of such cisterns, i.e. covers, screened breathers, screened warning pipes and vent pipe entry devices, and for cistern insulation. It gives methods oftestfor the evaluation ofthe properties of cisterns and covers made by any of the processes currently available. This British Standard applies only to cisterns that are manufactured from thermoplastics, and that have covers manufactured either from thermoplastics or from other manufactured materials having a thermoplastics layer on the inside face. It covers both circular and non-circular cisterns, but does not apply to flushing cisterns.