U.S. Navy Secretary Carlos Del Toro will wrap up his visit to Hawaii Monday as the service continues to work to resolve the months-long contamination of its water system that serves 93,000 people on Oahu, including military families, schools, businesses and civilians living in former military housing areas.

The Navy’s underground Red Hill fuel storage facility is the source of the contamination, which occurred when fuel spilled into facility’s fire suppression system in May, causing a rupture that brought jet fuel into the Red Hill water well.

The Environmental Protection Agency announced last week that it would be investigating the facility.

Military families affected by the contamination reported unusual rashes, vomiting and other ailments in the days after the spill.

Del Toro has been on Oahu since Friday. A Navy news release said he held a town hall with families, toured the Red Hill facility and visited affected Joint Base Pearl Harbor-Hickam neighborhoods to talk to residents.

After months of system flushing and other efforts, the Hawaii Department of Health has determined water in Red Hill housing and Pearl City Peninsula housing is now safe to drink again, but the rest of the Navy system remains tainted.

“This situation will remain unacceptable until all of the zones are within EPA and HDOH standards and all of our families are no longer impacted,” Del Toro said in the news release. “Our families in Oahu deserve transparency from their leadership at every step of this process.”

The Navy is part of the Interagency Drinking Water System Team formed in response to the contamination crisis and is working with DOH, EPA and the U.S. Army “to restore safe drinking water to Joint Base Pearl Harbor-Hickam housing communities through sampling and flushing, and the recovery of the Red Hill well.”

The Navy has been fighting a DOH emergency order issued in December that required the Navy to drain the facility’s tanks, which sit above a critical aquifer that provides much of Honolulu’s drinking water. The Pentagon has argued the state doesn’t have the authority to make that order.

The Navy is facing growing political pressure to shut down the Red Hill facility permanently. While in Hawaii, Del Toro also met separately with members of Hawaii’s congressional delegation and Gov. David Ige

“All of us are working tirelessly with a clear focus on ensuring the health and safety of the people of Hawaii, including our military families,” Del Toro said. “Despite immense challenges, we have made significant progress and we must continue to work comprehensively together if we are ever going to regain their trust.”