The US Navy found water that looked and smelled weird on an aircraft carrier last month, and it still has no idea why

• The Navy discovered last month that the water on the USS Abraham Lincoln looked and smelled strange.
• Testing found E. coli in the water, but Navy officials said it was unrelated to the odor and cloudiness.

Nearly a month after the US Navy discovered that the water aboard one of its aircraft carriers looked and smelled strange, the service still has no idea what caused the issue.

Sailors on the aircraft carrier USS Abraham Lincoln first noticed on September 21 that the water they drink and bathe in had an "odor and cloudy appearance." A Navy official told Insider on Tuesday that it's "not yet known" why the potable water on the ship had characteristics beyond what would traditionally be associated with safe, clean water.

The day after the unusual smell and appearance were detected, testing of the water supply revealed the presence of E. coli bacteria in a few of the ship's water tanks. The Navy waited weeks to issue a public statement on the contamination, finally doing so on October 13.

In that statement, however, the Navy said that the E. coli "was not related" to reports of the "odor and cloudiness in the water." It said additional laboratory testing from late September indicated "the water was within drinking water standards for pH, turbidity, aluminum, copper, lead, sodium, and hardness."

Following the release of that public statement, Insider questioned the Navy on why the water looked and smelled unnatural, specifically asking if there were other contaminants beyond the E. coli in the water supply.

"It is not yet known what caused the odor and cloudiness in the water, but USS Abraham Lincoln continues to work with Naval Sea Systems Command and Navy and Marine Corps Public Health Center to test the ship's water to determine if additional contaminants were present," Naval Air Forces Cmdr. Zach Harrell explained in his Tuesday statement to Insider.

"The three tanks that were found to have water with E. coli also contained the water with the odor and cloudiness," he continued. "Those tanks were immediately isolated and secured from the potable water system, and the odor and cloudiness in the water abated by Sept. 22."

"The affected tanks will be deep-cleaned and inspected during the ship's ongoing maintenance period," Harrell added, noting that "a thorough root-cause analysis is ongoing."

The Navy said last week that USS Abraham Lincoln returned to San Diego's Naval Air Station North Island earlier this month and that the carrier was connected to the city's water supply. The service added that bottled water was distributed to the crew and that there have not been any confirmed cases of illness related to the water.

Issues with contaminated water aboard US Navy flattops are not isolated incidents. A few days before finding issues with the water on the Abraham Lincoln, the Navy said it found what it referred to as "traces" of jet fuel in the aircraft carrier USS Nimitz's potable water.

A Nimitz sailor and their parents told Insider that the contaminated water situation on the ship was way worse than what the service initially revealed publicly. Navy and Marine Corps veterans later told Insider that jet fuel has actually been contaminating water on the flattops for decades and is a problem that has spanned multiple ships.