Estimating the burden of illness in an Ontario community with untreated drinking water and sewage disposal problems

The Hamilton-Wentworth regional health department was asked by one of its municipalities to determine whether the present water supply and sewage disposal methods used in a community without piped water and regional sewage disposal posed a threat to the health of its residents. Three approaches were used: assessments by public health inspectors of all households; bacteriological and chemical analyses of water samples; and completion of a specially designed questionnaire by residents in the target community and a control community. 89% of the 227 residences in the target community were found to have a drinking water supply that, according to the Ministry of Environment guidelines, was unsafe and/or unsatisfactory. According to on-site inspections, 32% of households had sewage disposal problems. Responses to the questionnaire revealed that the target community residents reported more symptoms associated with enteric infections due to the water supply. Two of these symptoms, diarrhea and stomach cramps, had a relative risk of 2.2 when compared to the control community (p less than 0.05). The study was successfully used by the municipality to argue for provincial funding of piped water.