This WaterMark Technical Specification specifies requirements for a composite piping system consisting of a stainless steel outer casing bonded to an inner layer of polypropylene (PP-R), which includes a contact layer of nano-antibiotic material. This system is generally intended for use in cold and heated water supply systems at continuous operating temperatures up to 80°C with short exposures up to 100°C and continuous working pressures not exceeding 1.4 MPa.