P PS-128 BIT type water pump is a non-automatic water pump produced by PT Tirta Intimizu Nusantara. The problem of water pumps received by the company based on customer complaints is used as a benchmark for the company in making improvements to quality where the percentage obtained is 5.93%. The target percentage of defects desired by the company is less than 3%, so the company wants an improvement in the quality of the production process for the PS-128 BIT water pump. This research aims to reduce the percentage of product defects so that it is given a proposal for improvements that will be made to improve product quality. This study used the Six Sigma approach through five stages of DMAIC. The define stage is carried out by identifying the process and characteristics of defects which are used as a benchmark for making improvements with SIPOC and CTQ diagram tools. The measure stage was carried out data processing using control map c with the resulting DPMO value of 51.000 and a sigma level of 3,135. The analysis stage was carried out using pareto diagrams to identify the dominant types of defects in the form of leaky mseal and leaky o-rings, fisbone diagrams, FMEA and FTAs. Based on fmea, the highest RPN values were 288 and 252 so that improvement proposals were given in the form of a mseal part inspection checklist, provision of supporting tools in the form of air dusten guns and part cleaning checklists. As a result of the implementation, there was an increase in the sigma rate of 3,262 with a DPMO value of 39.000.