To determine the impact of the introduction of borehole wells on water use patterns and the consequent risk of transmission of Schistosoma haematobium in 3 endemic villages in Kenya, we performed a survey (a 1:6 sample of affected households) to identify sources of water and types of water utilization before and after well introduction. Water usage was also determined in 2 unaffected neighboring villages not given borehole wells, but having continuous access to piped water from communal taps. Prior to borehole well construction, significantly more high-risk water use occurred in the borehole villages vs. comparison villages in terms of water gathered for cooking, drinking, dish washing, and bathing; residents of both types of villages preferred high-risk sources (marshes and ponds) for clothes washing. Following well introduction, there were significant declines in the use of high-risk water for drinking, cooking, and dish washing, but not for bathing or clothes washing. A higher proportion of individuals from the 3 borehole villages reported some type of continued contact with high-risk water sources. Despite well introduction and a 3 year chemotherapy program among school-aged children, a 21-28% incidence of infection persisted among children in the villages, suggesting minimal impact on transmission. Regular monitoring for S. haematobium infected snail sites showed no decline in the number or proportion of infected snails. Borehole well introduction can significantly alter some forms of water usage, but social and water quality factors may limit the ability of communal wells to reduce S. haematobium transmission.