This aim of this study was to determine water usage behavior and incidence of diarrhea during the summer months among people in rural areas of Turkey. Information was collected using a questionnaire during face-to-face interviews with people aged 18 years and over in their homes. Diarrhea was detected in 31.7% of the 543 households included in the study in the summer of 2003. The percentage of those living in the study area experiencing at least one bout of diarrhea was 10.0%. The diarrhea episode rate was 18.7%. A logistic regression model of factors that could influence the incidence of diarrhea showed that the reported distance between the septic tank and the well, the total monthly household income and water shortages of longer than 12 h had a significant effect on diarrhea incidence (P < 0.05). The fact that water shortages are the biggest risk factor for diarrhea points to the need for (i) health education to raise awareness and (ii) the supply of equipment to enable households to use both the first running water after a water shortage and the water they have collected during the shortage as drinking water. (C) 2007 Royal Society of Tropical Medicine and Hygiene. Published by Elsevier Ltd. All rights reserved.