PDAM Kab.Banggai is a service company that has the aim of meeting the needs in the field of clean water must provide the best service. The purpose of this research is to analyze service quality based on customer satisfaction and find out the factors that affect service quality to get a solution to the causes of problems based on service quality. This research will use the servqual method to measure service quality with the level of perceptions and expectations of consumers in the services provided by service providers. Furthermore, the Importance Performance Analysis (IPA) method is used in measuring the level of importance and performance so that the company can find out the attributes that need to be improved and maintained in service based on a Cartesian diagram and will produce a basis for customer satisfaction. After that, the Fishbone Diagram is used to analyze the consequences by finding and describing the factors that cause the existing problems. Then given the proposed improvements and submitted PDAM to be followed up by PDAM Kab.Banggai. The results of the Service Quality analysis of the quality of service of PDAM Kab. Banggai obtained a negative Gap in the Reliability dimension at attribute B5 (-1.200), in the Responsiveness dimension obtained a negative Gap at attribute C1 (-1.140), at attribute C2 with a negative Gap (- 1.120) and in the Assurance dimension with a negative Gap (-0.560). The results of the analysis using Importance Performance Analysis obtained 4 attributes that are among the top priorities for improvement, namely the attributes contained in quadrant I. The four attributes that are the top priorities for improvement are the ease with which customers can submit complaints online to the PDAM, employees are responsive when answering complaints from customers through online media such as whatsapp, officers contact customers when they cannot fulfill the specified repair promise and the use of PDAM services Kab. Banggai is guaranteed to be safe when making payment transactions. The proposed improvements given to PDAM Kab. Banggai are Attribute D2, namely conducting a re- check before making payment bills to customers, collaborating with third parties such as banks and outlets (indomaret, alfamidi, etc.) and making payment applications directly linked to PDAM accounts so that there is no manipulation during the payment process. Attribute C2 is instilling a sense of responsibility in officers and openness to customers to contact customers as soon as possible if something happens or cannot fulfill the specified repair promise, the need to make SOPs so that they have standard provisions for contacting customers if they cannot fulfill repair promises and provide facilities to contact customers. Attribute C1, namely recruiting Customer Service and implementing a 24-hour work shift system to be available if there are complaints via messages or calls, implementing online complaint services for 24 hours to be responsive to answering customer complaints and providing social media accounts that are always updated to provide information about PDAM and responsive when there are complaints from customers online. Attribute B5, namely implementing a work shift system for officers who are available when there are complaints via messages or calls, implementing online complaint services through social media and providing media for customers to submit complaints online such as providing PDAM contact numbers that are always active 24 hours. For further research, it is hoped that it will be able to research to implement the proposed improvements provided and analyze the quality of service after implementing the proposed improvements provided by the author so that the effectiveness of the services that have been implemented can be known.