Around 650 Hawaii residents have been relying on bottled water since March, after the state health department detected synthetic chemicals, known as PFAS, in the local water system.

The contamination dates back to at least October, when Hawaii’s Department of Health detected the chemicals in one of two wells that serve Kunia Village, an affordable housing development on O’ahu.

The department announced in January that the levels detected exceeded the Environmental Protection Agency’s proposed limit for two types of PFAS — called PFOA and PFOS — in drinking water, as well as Hawaii’s state limit, above which communities are expected to treat their water systems or provide an alternative source. The concentration is under the current EPA limit, however.