This International Standard gives guidance for the classification and design of hot and cold water pressure systems which use plastics pipes and plastics or metal fittings. It establishes a classification system for common service conditions for pressurized hot and cold water systems. It gives a basis for evaluation and design of thermoplastics pipes and fittings in relation to the system performance requirements. It applies to plastics piping systems used to carry water a) in distribution systems of hot and cold water, including potable water, and b) in transportation systems of hot water for heating, under design pressures up to at least 10 bar 1) at 20 °C and up to 10 bar at temperatures according to the class of application (see Table 1). For values of TD, Tmax and Tmal in excess of those in Table 1, this International Standard is not applicable. Acceptance of any pipe(s) and/or fitting(s) made from a specific grade of material is subject to the relevant product or systems standard and the requirements detailed there.