This British Standard specifies requirements for the physical properties and performance of both rubber and PVC hot water bottles, designed for complete or partial filling with hot water by the user.
BS 1970:2001 history
2012BS 1970:2012 Hot water bottles manufactured from rubber and PVC. Specification
2006BS 1970:2006 Hot water bottles manufactured from rubber and PVC - Specification
2001BS 1970:2001 Hot water bottles manufactured from rubber and PVC - Specification