This study suggested eco-friendly coating materials that have anti-bacterial capacity by using nano-silver, could be prevent the drinking water pollution in a water tank. Various organic injurious compounds such as Toluene, Ethylbenzene, Xylene, phthalate and MIBK were detected in the elution of a water tank coated with epoxy. In case of epoxy materials without adding nano-silver, bacteria look like decreased due to toxins such as organic compounds. Heavy metals and organic compounds were not hardly detected in water tanks coated with Hwangto and Ceramics which were eco-friendly materials. Hwangto and Ceramics were coated by nano-silver more than them without nano-silver can extremely limited the growth of bacteria.