Water Quality Study

Environmental Health

Johns Hopkins Center for American Indian Health conducted a study to determine the causes of acute gastroenteritis (i.e., vomiting and diarrhea) and to evaluate potential associations between acute gastroenteritis and household drinking water quality, availability, and handling practices.

Why water safety is critical

Access to safe drinking water for people living in the Navajo Nation can be challenging because of the rural nature of many communities. About 30-35% of reservation households are not connected to public water systems compared to 0.6% of households nationally and 12% for American Indian tribes overall. 

Of the approximately 14,000 Navajo households and 54,000 individuals without direct public water access, many collect water from unregulated, untreated, shallow-well sources. These water sources are known to be frequently contaminated by fecal bacteria.

About the water quality study
Researchers at Fort Defiance and Chinle partnered with Indian Health Service medical providers to identify community members arriving at clinics with gastroenteritis. In addition, a comparison group of people of a similar age who were treated at the medical facility for anything other than gastroenteritis were also invited to participate. Stool samples from the study participants were tested for viruses, bacteria, and parasites that cause vomiting or diarrhea. In addition, samples of drinking water from participants’ homes were tested for waterborne pathogens, coliforms, and residual chlorine.

This study was conducted in 2010-2011. Of water samples tested, 8% of the water samples tested positive for E. coli and 44% tested positive for total coliforms. The parasite Cryptosporidium was detected in one water tested. Ten (17%) of the 46 stool samples were positive for viruses and parasites such as norovirus, sapovirus and Cryptosporidium hominis. All study participants were notified of water and stool test results.

The Johns Hopkins Center for American Indian Health is working to identify appropriate strategies to improve access to safe water and improve health.

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