Water sector reform was supposed to enhance water provision in all Counties of Kenya. However the implementation process has not been effective. It is in this regard that the study assessed the implementation of water sector reforms on socio-economic development programs in Mandera County. To achieve this objective the study analyzed the effects of operation cost, community participation, policy, and sustainability concerns on socio-economic development programs. The study employed a descriptive research design which sought to establish factors associated with certain occurrences, outcomes, conditions or types of behavior. The target population was 540 and the sample size was 10% of the target population which was 54. Questionnaires were used to collect Data. Majority comprising 64% of the total participants indicated that operational cost affected socio-economic development programs in Mandera County, 68% of the total participants indicated that community participation influenced socio-economic development programs in Mandera County, 76% of the total respondents indicated that policy affected socio-economic development programs in Mandera County and 72% of the total participants indicated that sustainability concern influenced socio-economic development programs in Mandera County. The water supply agency should ensure that operation costs are low, community participation should begin as soon as a community has requested a water supply facility. A policy framework should be put in place to help streamline the water sector. Water should not be over-exploited but naturally replenished and facilities should be maintained in a condition which ensures a reliable and adequate water supply.