During a severe drought Port-au-Prince, Haiti, lost hydroelectric power for 10 weeks. This led to water shortages in areas of the city dependent on water supplied from electrically driven pumps. In a study of the impact of water restriction on disease, 400 families were randomly selected from two urban areas differentially affected by the water shortage. Disease in children was found to be related to quantity of water used, socioeconomic status, employment of head of household, and family size. The methods used in this study are recommended for the investigation of the relationship between water quantity and health.