In this chapter, we discussed the corrosion and corrosion protection in drinking water systems. The corrosion of the drinking water distribution system (DWDS) basically depends on the pH of water, the hardness of water, alkalinity of water, buffer intensity, total dissolved oxygen, and inorganic carbon. The indices LSI and LI are discussed. The inhibitor effects of phosphorus and sulfate are discussed. The effect of the presence of metal ions like Zn, Mn, Cu, Cd and Pb on DWDS is discussed. The temperature effect, microbiological induced corrosion and galvanic corrosion processes are briefly presented. The stagnation of water and leaching of Cu, Zn in commonly used DWDS is discussed with the toxicity of iron-based deposits in DWDS. Also, the protection of DWDS from copper pitting is presented. Some of the protection methods to reduced corrosion in steel pipes, Al and Mg-based alloys are also discussed.