The U.S. Navy and Environmental Protection Agency are working on a new plan to sample and test Pearl Harbor’s drinking water amid concerns that what the military calls “low-level detections” of petroleum in the water could be making people sick.

Military officials have been monitoring Pearl Harbor’s drinking water since a fuel spill at the Navy’s Red Hill storage complex contaminated the system in 2021. At the time, families living on the water line reported serious illnesses, including rashes, neurological issues and gastrointestinal problems. Some people required hospitalization.

In response, the contaminated water system was flushed with clean water, and the Navy agreed to sample and test the system for total petroleum hydrocarbons for two years. That so-called Long-Term Monitoring Plan was set to end by this month.

Total petroleum hydrocarbons have been detected throughout the last two years, though at levels the Navy considers low. During the testing period, the Navy has maintained there were no “exceedances” of the environmental action level, or EAL, for total petroleum hydrocarbons. The EAL is not an evidence-based safety threshold but rather a limit set by regulators that would trigger a response under the monitoring plan.

However, residents on the water line continue to report ongoing, reoccurring and new health symptoms they believe are connected to the water. In December, the EPA published a report validating these concerns and calling on the Navy to investigate the root cause.

On Wednesday, the Navy said personnel from the military and Hawaii Department of Health are collecting samples this week from residences and the well the system relies on, called the Waiawa shaft. The Navy and regulators are also working on developing a “voluntary” agreement referred to as an Extended Drinking Water Monitoring Plan, according to a Navy press release.

“We hear and understand the community’s concerns, and I want the community to know that the Navy will voluntarily continue to monitor the drinking water system after the (Long-Term Monitoring) program ends next month,” Rear Adm. Steve Barnett, commander of Navy Region Hawaii, said in a statement.

“The health of our military members, families, and neighbors served by the (Joint Base Pearl Harbor Hickam) drinking water system is paramount and we are doing this to continue to go above and beyond to ensure their safety and well-being.”