After days of testing, the U.S. Navy has confirmed the existence of petroleum products in a well water sample taken near Hawaii’s Pearl Harbor military base. The well, which is connected to the Navy’s water system, has been closed since Sunday while officials investigated reports of tap water smelling like fuel.

According to a Friday statement from the Navy, it collected 14 water samples from different parts of the water system on Monday. Thirteen tests came back negative, but one sample from the Navy’s Red Hill well came back positive for petroleum hydrocarbons, which the EPA describes as “a large family of several hundred chemical compounds that are derived from crude oil.” A separate test also confirmed petroleum hydrocarbon vapors.

Hawaii’s Department of Health said on Wednesday that a sample from Red Hill Elementary School, which was collected Tuesday, came back positive for a petroleum product in a preliminary test result. The samples were then sent to Eurofins Scientific in California for further analysis. It is not clear whether this sample was the one that the Navy confirmed was positive on Friday.

“Now with multiple indications that the source has been identified and isolated, the Navy is developing a plan to restore the potable water system to EPA standards, identify how this contaminant got in the well, and fix the well,” the Navy said Friday. It added that it will work with the state’s department of health to update guidance for local residents and service members.

It is not clear exactly what kind of petroleum products were detected or how they got into the system.

The Navy had shut down the Red Hill well, which draws on the Moanalua-Waimalu aquifer located 100 feet below the Navy’s fuel storage tanks on the island of Oahu, out of an “abundance of caution” on Sunday, a spokesperson told the Associated Press.

On Tuesday, Hawaii’s Department of Health told residents within the Navy’s water system to avoid “using the water for drinking, cooking, or oral hygiene” after it received multiple reports of “fuel or gasoline-like odor from consumers of the Navy’s Joint Base Pearl Harbor-Hickam (JBPHH) water system, including the Aliamanu Military Reservation, Red Hill and Nimitz Elementary Schools, and military housing.” The department said all of the complaints came from people using the Navy’s water system. 

The department said the Navy is responsible for ensuring its water is safe for all of its customers — and if it’s not, the Navy must provide “alternative sources of drinking water for human consumptive uses as deemed necessary.” In the days since the water was declared unusable, the Navy said it has distributed bottled water and will soon have portable showers available for base residents. Certain authorized residents affected by the water crisis can also go to hotels and will be reimbursed by the government, military officials said during a press conference. 

On Thursday night, state officials criticized the Navy’s response to the reported issue. 

“(The Navy is) paralyzed in finding a solution to this problem,” Senator Glenn Wakai said, according to a tweet from the Hawaii State Senate. “Last night they were saying this is a natural disaster and that’s how we should look at this. This is a man-made disaster. The Navy really has to pick up the pace in which it addresses solutions.”

The Navy’s system provides water to about 93,000 residents living in and near Pearl Harbor, the AP reported.

“The Navy’s priority is keeping Sailors, civilians, their families, and all of those who live and work on Joint Base Pearl Harbor Hickam property and who use the Navy’s water safe and healthy,” the Navy said on Friday.

Nearly two weeks ago, the Navy reported a leakage of water and fuel at the Red Hill fuel tank farm, where the Moanalua-Waimalu aquifer is located. It alerted local health authorities and said in a statement that “there are no signs or indication of any releases to the environment, and the drinking water remains safe to drink.”