Some villages in American Samoa are drinking water that has been rated as the most contaminated throughout the mainland and the US territories.
A team from the US Environmental Protection Agency say village water in Onenoa, Afono, Vatia, Fagalii and Fagamalo is the most unhealthy they have found in their research.
The group's in the territory to conduct sanitary surveys of village water and water provided by the American Samoa Power Authority.
An engineer from the EPA, Steven Sallach, says the water in the villages isn't sterilised or filtered.
"And any diseases or animals that are up stream of those sources [water] will contaminate the water. And there are many leaks down below that goes through the stream and so those are pathways also for contamination."
The local EPA says that since 2005 the water in the five villages has tested positive to the presence of bacteria.
The U.S team says a similar village water system in Fiji regularly tested positive for E.coli and that led to a typhoid outbreak.