Maui Department of Water Supply releases first test results from Lahaina, Upper Kula

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The Hawaiʻi State Department of Health and the US Environmental Protection Agency continue to advise and provide technical assistance to the Maui Department of Water Supply. On Wednesday, Aug. 23, the Maui DWS released test results from the first 27 samples collected from the Lahaina and Upper Kula drinking water systems.

The county water purveyor is responsible to communicate its Unsafe Water Advisories to customers and to provide alternate drinking water sources to the Lahaina and Upper Kula communities impacted by the advisories. DOH is releasing additional context on the initial water test results to support the DWS.

The results of the first drinking water tests released by the Maui DWS were collected jointly by DOH and Maui DWS staff on Aug. 14. Initial testing was for 23 regulated volatile organic compounds (VOC) listed in the EPA drinking water method 524.2. Additional testing may be recommended as work continues.


Twenty-five of the 27 samples did not detect any of the VOC compounds. One sample in Lahaina collected from Kaniau Road detected 0.7 parts per billion of benzene, a byproduct of wildfires. The maximum contaminant level, which is the maximum allowed of a contaminant in water which is delivered to any user of a public water system, is 5 parts per billion. Out of an abundance of caution, Maui DWS isolated this part of the system with the hydrant to protect the rest of the system.

While the initial results are reassuring, the Maui DWS’ Unsafe Water Advisories remain in place at this time. The process to amend the Unsafe Water Advisory will be based on a comprehensive review of multiple lines of evidence. 

A sample collected from the Upper Kula Treatment Plant detected the presence of toluene and xylenes at a level less than 0.5 parts per billion. The maximum contaminant level for toluene is 1,000 parts per billion and total xylene is 10,000 parts per billion. The source of the Upper Kula system was tested as part of DOH’s standard operating procedures. Additional monitoring is underway to ensure that the Upper Kula Treatment Plant continues to meet all primary drinking water standards. The Upper Kula Treatment Plant is not in an area under the current UWA. Based on these results the DOH does not believe the UWA needs to be amended at this time; however further investigation is ongoing.


The initial testing is the first step in a rigorous process to ensure water is safe to resume drinking. That process may include additional testing, isolating the impacted parts of the system, flushing impacted parts of the system to remove contamination, and possibly replacing certain parts of the water distribution system if determined necessary.

Together, DOH and Maui DWS staff continue to collect water samples from across the Lahaina and Upper Kula communities. All agencies are united in our work to prioritize health and safety. The shared goal is to restore drinking water as soon as we can be certain of its safety and to keep the community informed along the way.

To aid the public in better understanding the test results, the following information is provided:


Detection Limit: refers to a minimum concentration of an analyte that can be measured above the instrument background noise. 

What is instrument background noise? Instruments have detectors that convert any target analyte entering the detector into an electrical signal that can be measured. Using a calibration curve, this signal can be converted into a concentration. Instrument noise is due to the normal, random generation of electrical signal from sources other than the target analyte. Some causes are radiation, magnetic fields, loose connections or static. They have nothing to do with the specific sample being analyzed.

What is an MCL? The maximum concentration level or (MCL) is the maximum concentration of a chemical that is allowed in public drinking water systems. The MCL is established by the United States Environmental Protection Agency (EPA).

What is μg/L? The symbol μg = microgram. One microgram is one millionth of a gram and one thousandth of a milligram. So if the MCL reads 2 μg/L that is 2 micrograms per liter. It is also referred to as parts per billion (ppb). 

What is ND? ND stands for not detected.


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