Laboratory contamination was the cause of increased low levels of total petroleum hydrocarbons detected in the Navy’s drinking water system since last summer, the Navy Closure Task Force-Red Hill announced Wednesday. The TPH detections were not associated with jet fuel contamination in the underground Red Hill Bulk Fuel Storage Facility, the Navy said.

According to the Navy, the detections were determined to be false positives caused by chlorine, which is added to drinking water to disinfect it before it reaches consumers. The findings come from an investigation by the Task Force’s “Swarm Team,” composed of members of the Navy and Department of Defense, the Environmental Protection Agency and the state Department of Health, as well as other contractors, that was assembled to evaluate potential causes of the low-level detections.

“The results of the team are now final. We’ve validated the data and we’re confident in why we’ve seen these low-level detections,” Chris Waldron, an environmental engineer for the Navy and a member of the Swarm Team, said Wednesday in a Navy news release. “This information is helping the Navy to voluntarily refine its testing processes.”

The Navy said test results of 8,500 samples taken during the long-term monitoring period, which began in March 2022 and ended at the end of last month, are still valid. The low-level detections reflected in these results were determined to be “inflated due to a chemical reaction during laboratory analysis and not related to TPH concentrations in the water,” the Navy said.

Following an influx of TPH detections in late 2023, the Swarm Team, which was assembled in January, met daily to review test results and considered multiple possible root causes, before concluding that the increased detections resulted from the laboratory method, known as Method 8015, being used to analyze test samples.

“There is no approved regulatory method to test for TPH in drinking water, so EPA had directed that we use a wastewater testing method approved by the EPA,” Waldron said. “That process doesn’t account for the chlorine in drinking water and was returning results that mimicked TPH.”

According to a Navy fact sheet, Method 8015 used a chemical that “was found to interact with chlorine present in the drinking water samples, producing increased TPH readings in the sample results.” These readings differed from that of the reading for jet propellant 5.

The Swarm Team recommended the Navy use a different EPA-approved method — called Micro-Extraction With Quenching (MEQ) — to prevent cross-contamination and chlorine presence in samples in their analyses. The MEQ method has an additional step in its process that uses sodium thiosulfate to neutralize chlorine, eliminating false positives. According to the Navy, this method does not affect any existing concentration of fuel-related petroleum in the samples.

To test the new method, the Navy collected almost 600 samples from residences, schools and other locations on the Joint Base Pearl Harbor-Hickam water system in February and March to analyze using both its original testing method and the new MEQ method. Testing both methods side by side “conclusively demonstrated” that the MEQ method eliminated false positive detections, the Navy said.

To ensure the MEQ method would still detect fuel-related petroleum, the Navy injected some water samples with a “known concentration of jet propellant 5” at the lab and verified that the detection would still appear, verifying that the new method “accurately and precisely detects fuel-­related petroleum if it is present in drinking water.”

The Navy said that all samples collected throughout the investigation indicate that water on the JBPHH water system “continues to comply with all state and federal drinking water standards.”

In November 2021, fuel from the Red Hill Bulk Fuel Storage Facility leaked into the JBPHH water system, affecting 93,000 people who live in housing areas on the system, including service members, their families and civilians.

The Navy is the water purveyor for the water system and is therefore responsible for maintaining water quality, including water testing, under regulatory oversight by DOH and the EPA.

The Swarm Team’s findings come just over a month after the Navy released its preliminary plumbing assessment report, which investigated plumbing at 10 homes from October to December after multiple complaints of air and water quality issues from residents on the JBPHH water system.

In January, residents again complained to the Navy, DOH and the EPA about issues with their air and water quality. The Red Hill Community Representation Initiative received over 50 reports of issues like visible sheens on the water and strong odors and chemical tastes, as well as 70 responses to a poll on the Joint Base Pearl Harbor-­Hickam Water Contamination Support Facebook group page and other complaints posted on neighborhood social media pages.

“There is still work to do,” NCTF-RH deputy commander Rear Adm. Marc Williams said in the Wednesday release. “We are confident there is no JP-5 or fuel in the water, but we will keep testing and assessing the data to determine what is causing some of the reported smells, sheens and health concerns residents have expressed.”

The Navy announced in mid-February that it will continue its water quality monitoring through its “Extended Drinking Water Monitoring” program, which will build on the LTM plan. The Navy also said it expanded its drinking water quality action team with “enhanced capabilities,” like new specialists and investigators to evaluate consumer water quality issues.