Social deprivation and the public health risks of community drinking water supplies in New Zealand

Study objective: Quantitative evidence linking environmental exposures and social status at sub-national scales is surprisingly limited. This study investigated the public health risks associated with community water supplies in relation to social status in New Zealand. Design: An ecological study using a Geographic Information System (GIS) to compare the grade of community water supplies with an index of social deprivation for small areas. Setting: New Zealand. Participants: The New Zealand population usually resident in meshblocks ( census areas) with a community water supply (70% of the 1996 population of 3.6 million people). Main results: People living in deprived areas are exposed to greater public health risks from community water supplies. In urban areas, the odds of water supplies being high risk were 3.76 times greater for the most deprived decile compared with the least deprived decile (95% CI: 2.95 to 4.78). Conclusions: It is probable that deprived communities in New Zealand are experiencing a disproportionate burden of adverse health effects as a result of poor water quality.