Objective To learn the status and compare the effect of improving drinking water and lavatories in potential endemic areas of schistosomiasis in the Three Gorges Reservoir Area. Methods A cluster random sampling method was adopted and a questionnaire survey was conducted to four selected villages and towns before and after organized and large scale drinking water and lavatories improvement in the potential endemic areas of schistosomiasis in the Three Gorges Reservoir Area. Results A total of 807 households in four demonstrate villages and towns were investigated for the baseline survey, while 856 households in the same four villages and towns were investigated for the terminal survey. The popularity rate of using tap water from waterworks went up from 33.58% to 66.12% (P=0.000); the summation of popularity rate of using tap water from both waterworks and water tower made by local residents went up from 76.33% to 96.38% (P=0.000); and the popularity rate of using decontaminated lavatories went up from 53.68% to 78.85% (P=0.000). According to Chi-square test, there were significant differences compared with the popularity rate before improvement (Plt;0.05). Conclusion The condition of intervention villages and towns gets greatly improved through the organized and large scale project of improving water quality and lavatories decontamination, and the potential danger of schistosomiasis is obviously reduced in the Three Gorges Reservoir Area.