We developed the remodeling techniques of water storage tanks and the residual chlorine remaining devices. Eco-TIR((Total Internal Remodeling) is remodeling technique that cover the inside wall of concrete tank with SMC(Sheet Mold Compound) Block. Eco-SL(Stainless steel Lining) and Eco-GS(Glass sheet) is similar to Eco-TIR(Total Internal Remodeling) but stainless steel or glass tile is substituted for SMC block as a cover material. We tested the residual chlorine remaining devices and the results are as follows. First, it was estimated that mixing efficiency is increased if inflow energy to the water tank is used in the results of variation of residual chlorine concentration. Secondly, result showed that the removal percent of residual chlorine concentration was up to 90% by using ACF filter and feed water of high residual chlorine concentration can be controlled to 0.2mg/L〜0.4mg/L by using ACF and by-pass of inflow to the water tank. Also, in the water tank inlet pipe of 3-ways out using inflow energy is more effective in mixing than conventional inlet pipe. It is expected to enhance the safety of service water and management efficiency by applying mentioned techniques properly.