This paper briefly discusses the ITER Tokamak Cooling Water System design and operation and the technical approach used in the selection and evaluation of the piping materials. Dual certified 316/316L low carbon austenitic stainless steel is recommended for the cooling water system piping. The remaining challenges include presence of copper and CuCrZr alloy at water flow velocity up to 12 m/s, uncertainty in the evaluation of the water chemistry and corrosion potential during neutron flux (O2, H2O2), crevice corrosion of 1000 tons of borated and ferritic steel plates, and the effect of high magnetic fields on the corrosion and deposition processes and the forces generated by interaction with delta ferrite.