In the Kraft recovery boilers plant, demineralized water is an important element in the heat exchanger process for the production of electricity and steam. Demineralized water exchanges ion with resins. The current problem of demineralized water qualification has high conductivity value in resin recirculation rinse. This makes the rinsing process take much longer compared with the standard and it decreases the production capacity of the demineralized water.  In this paper using the Six Sigma method to reduce the duration of the recirculation rinse process. Cause and Effect Matrix and Failure Mode Effective Analysis (FMEA) were adopted to select the factors that affect the recirculation rinse time. The 2^k-1 factorial design method was used to determine the potential preliminary root causes. After that a series of factorial design experiments was conducted to identify the factors that significantly impact the recirculation rinse period. Having done all that, the guidelines to setup the process parameters to effectively regulate the rinse period were established. The result showed that the process can reduce the recirculation rinse time from 150 minutes to 23 minutes. In addition, the production of the demineralized water increases to 10,780 cubic meters per month or 13% more than previously obtained.