Maui County, Hawaii: drinking water report. Maui County encompasses the islands of Maui, Molokai, and Lanai, serving communities from Kahului and Lahaina
Maui County encompasses the islands of Maui, Molokai, and Lanai, serving communities from Kahului and Lahaina to Kihei and Hana. Water supply here depends heavily on surface sources (streams, reservoirs), groundwater wells, and private catchment systems, particularly in remote areas. The island geography creates unique challenges, with some residents on county systems while others maintain their own water collection infrastructure.
Maui County's water quality reflects both its volcanic geology and its agricultural history. The island's aquifers naturally filter water through porous basaltic rock, which typically removes many contaminants but can also concentrate certain dissolved minerals. Lead rarely poses a widespread problem in the main public systems due to newer infrastructure and naturally soft water, though older properties in historic towns may still have lead service lines or plumbing components that warrant attention.
Agricultural runoff presents the more pressing concern across the county. Decades of pineapple and sugarcane cultivation (though most plantations have now closed) left a legacy of pesticide residues in some watershed areas. Dibromochloropropane (DBCP), a soil fumigant banned in 1979, continues to appear in certain wells at detectable levels. Atrazine and other herbicides occasionally show up in surface water testing, particularly during heavy rainfall events that flush agricultural lands. The state Department of Health monitors these legacy contaminants, but the problem illustrates how past land use affects current drinking water decades later.
Per- and polyfluoroalkyl substances (PFAS) testing in Hawaii remains limited compared to mainland states, though the EPA's latest monitoring requirements are expanding coverage. Military installations on neighboring islands and former industrial sites raise questions about potential contamination pathways. Private catchment systems, common in rural Maui County areas like Hana and upcountry Maui, face different risks entirely. Rainwater collection avoids groundwater contaminants but requires vigilant maintenance to prevent microbial growth, sediment accumulation, and contamination from roofing materials or bird droppings.
If you rely on county water, request your utility's most recent water quality report and ask specifically about pesticide testing results for your service area. Private catchment users should test annually for bacteria and consider filtration for sediment and potential chemical deposition from atmospheric sources. Check your water for testing data in your area, review our water filter guide to match treatment options to your source type, read the detailed report on contaminants of concern in island systems, or visit the Hawaii state page for broader context on the state's water quality patterns.