Kenya is a predominantly arid country with limited water sources. As at 2019, access to improved water and sanitation was estimated at 63 percent and 31 percent of the population, respectively, compared to the target of universal coverage by 2030 (The Kenya Institute for Public Policy Research and Analysis -KIPPRI, 2019). To address this need to distribute this scarce resource, and in keeping with the SDG 6 goal of universal access to clean water to all, the government’s efforts and focus was shifted to water projects. Whereas some gains have been made towards this goal, a Water Services Regulatory Board (WASREB) report on the performance of regional water utilities noted with concern that the worst performer was Mombasa County (seventh year in a row) and further highlighted with concern a continued decline in the performance of Kilifi County. Despite the numerous interventions in the water and sanitation sector in these two counties, there still lies a gap in attaining the SDG-6 agenda and projects continuously fail to perform as speculated. Deviation and changes of project scope mid-way has led to costly overruns both on time and cost hence the need to consider how to improve performance of water projects in the two counties. This study aimed at investigating the effect of scope control on performance of water and sanitation projects in Mombasa and Kilifi Counties, Kenya. The study was anchored on the management theory. 14 water projects were targeted with 46 respondents. Pilot tests showed the instrument was valid and reliable as confirmed by the supervisor and Cronbach Alpha results of 0.787. The SPSS version 25.0 and Ms. Excel were used for descriptive, regression, correlation and diagnostic tests. Correlation analysis results showed positive and significant association for scope control (r=.741) and the regression analysis yielded a regression coefficient of (β=.499), and a (p<0.05) indicating significant effect to performance of the water and sanitation projects. The study established that 55.8% change in performance of water and sanitation projects was due to scope control. Scope control involved continually updating project teams and monitoring project activities that improved performance of the water projects. Thus, it was concluded that performance of water and sanitation projects were influenced by scope control. It was recommended that scope control be incorporated when seeking to improve performance of the projects,

Keywords : Scope Control, Project Performance, Project Plan Updates, Changing Requests, Evaluating Project Progress.