Operation efficiency is critical for the smooth running and sustainability of water utilities. Employee engagement is integral to the operational efficiency of non-profit organizations in Kenya, including water service sector. Studies show that when the employees are appropriately engaged, managed and monitored, the organizations will avoid unnecessary losses and costs, achieving operational efficiency. This research scrutinized the effect of employee engagement on the operational efficiency of water service providers in Meru County. The objectives analyzed the variables of delegation, consultation and unions and their influence on the operational efficiency of Water Service Providers in Meru County. The study was anchored on three theories: Classical scientific, AMO, and social exchange theories. The Research was conducted on two water service providers: Imetha Water and Sanitation Company Limited and; Meru Water and Sewerage Services. The target population was 200 employees involving the corporate management team, middle management, and operative employees. The researcher selected 132 sample respondents from the population for the study. The researcher adopted an expository research design approach. Data was gathered using questionnaires. Content validity was used in the study, and Cronbachs Alpha was employed to measure the reliability of the research instruments. KMO and Bartlett Tests were carried out to test the validity of the research instruments. Data collected was analysed and evaluated using SPSS (Version. 21) and presented in charts, tables, and graphs. The variables of the influence of employee engagement were correlated against the operational efficiency of water service providers using the Pearson product-moment correlation coefficient. The study hypothesis was tested using a two-tailed normal distribution test at a 5% significance level. The results indicated a P value was 0.000 (P< 0.05) implying that employee engagement had a significant effect on operation efficiency of water service providers in Meru County. The study recommended that the WSPs adopt employee engagement strategies improve their operational efficiency for sustainability purposes.