A new study from the University of North Carolina at Chapel Hill has revealed that in one county of the state, some predominantly African-American neighbourhoods have a complete lack of access to the municipal water system.

As a result, the residents are exposed to higher quantities of microbial contaminants through their well water.

The findings, published online in the American Journal of Public Health, follows earlier work that identified neighbourhoods of non-connected African-American residents, surrounded by mostly white neighbourhoods that do have municipal connections. Further research determined that the mainly black neighbourhoods were more likely to visit hospitals for acute gastrointestinal illness than those with municipal systems.

The latest study undertook water quality surveys in the same areas, and laboratory tests showed that residents are being exposed to significantly higher levels of microbial contaminants.

Nearly 30% of the 171 private well water samples tested positive for coliforms, and over 6% tested positive for E. coli. Samples from the municipal system showed both contaminants at levels far below 1%.

The study authors estimate that 20% of the under-served communities visits to emergency departments for acute gastrointestinal illness could be prevented if municipal water services were extended.