Army officials responding to petroleum contamination of the Navy’s water system said science will dictate when displaced families will be notified it is safe to return to their homes.

During a Thursday evening town hall, members of the Army’s Task Force Ohana said flushing of the Navy’s water distribution system at the Aliamanu Military Reservation and possibly Red Hill communities, which together contain more than 1,600 homes, will continue until tests show the water is safe to use again.

The Navy’s Joint Base Pearl Harbor-Hickam water system provides water to about 93,000 people, including those on the Army-run communities at Aliamanu and Red Hill.

“There’s a process that we’ve got to follow here,” Maj. Gen. Joseph Ryan, commander of the 25th Infantry Division, said during the town hall held at the Aliamanu Military Reservation chapel. “We’ve known all along that the process is iterative, and it wasn’t just something we were just going to glide right through. It’s all based on the science. … We’re going to re-flush the system until we get the results we want.”

On Sunday the Army announced in a Facebook post that it had received test results after an initial flushing of the Aliamanu water distribution system that did not meet U.S. Environmental Protection Agency and state Department of Health standards for safe drinking water.

It’s still waiting for test results from a recent flushing at Red Hill.

The ongoing contamination at Aliamanu means it’s likely residents won’t be able to return to their homes until mid-February, the Army said.

“We know this is not the news that residents of AMR want to hear, but it is the approach we must take,” the post said.

That timetable contrasts with top Navy officials who said Dec. 29 that it could clean its water distribution system by the end of January.

Col. Alicia Masson of the Army’s Environmental Command said during the town hall that under a plan devised jointly by the Navy, Army, EPA and DOH, the water will be flushed, tested and flushed again until test results show it meets safe drinking water levels.

“Science is going to tell us you’re safe, not someone’s rank and not an order,” Masson said.

The emphasis on following the data was meant to ensure the health of affected military families is prioritized while the water distribution system is being cleaned. Many residents are enraged that the Navy allowed them to drink contaminated water even though it was known for months that there was petroleum in its water system.

The Navy had said the water was safe to use despite waves of reports from people who complained of ill effects and reported seeing and smelling petroleum in the water. Several thousand families have been displaced because of the contamination.

The water distribution system is believed to have been contaminated by a spill from the Navy’s massive underground Red Hill fuel storage facility, which sits above a major source of water for Oahu. For years the Navy has fought efforts to shut down or relocate the facility despite its history of fuel leaks.

Military officials have argued the fuel facility is vital to military operations in the Pacific region.