Objectives. We investigated the effects of failing sanitation, poor housing conditions, and fecal pollution in runoff water on the health-particularly the incidence of diarrheal disease-of residents of low-cost housing settlements in Cape Town, South Africa. Methods. In November 2009, we conducted a cross-sectional survey with structured interviews in 4 communities (n=336 dwellings; 1080 persons). We used Colilert defined-substrate technology to determine Escherichia coli levels in runoff water samples taken from the study communities. Results. Almost 15% of households disposed of soiled products in storm water drains and 6% disposed of soiled products in the street. In only 26% of the dwellings were toilets washed daily. Approximately 59% of dwellings lacked a tap near the toilet for hand washing, and 14% of respondents suffered 1 or more attacks of diarrhea in the 2 weeks preceding their interview. E. coli counts of runoff environmental water samples ranged from 750 to 1580000000 per 100 milliliters. Conclusions. A holistic and integrated approach is needed to improve housing quality and sanitation among Cape Town's low-income citizens. [ABSTRACT FROM AUTHOR]