Free Hawaii water report: PFAS & lead levels for every water system, worst-affected cities, and EPA violations. Check your ZIP.
Hawaii's drinking water comes from a source most states do not have: volcanic rock aquifers. The islands' basalt geology creates highly productive aquifer systems where rainfall percolates through porous lava rock and collects in freshwater lenses floating atop denser saltwater. This groundwater supplies approximately 90% of the state's drinking water for its roughly 1.4 million residents. Surface water supplements the supply on some islands, particularly for agricultural use, but groundwater is the backbone.
The Hawaii Department of Health (DOH) Safe Drinking Water Branch oversees about 140 public water systems, with the Honolulu Board of Water Supply serving the largest population on Oahu. The island aquifer model creates both advantages and vulnerabilities: the water is naturally filtered through volcanic rock and tends to be high quality at the source, but each island's supply is finite and isolated. Over-pumping draws saltwater into the freshwater lens, and any contamination that reaches the aquifer has no alternative source to blend with.
This isolation makes every contamination event in Hawaii more consequential than it would be on the mainland. There is no neighboring state's river to draw from, no distant reservoir to pipe in. When an island's aquifer is compromised, the options narrow fast.
PFAS contamination in Hawaii came into national focus not through routine monitoring but through a crisis. The Red Hill Bulk Fuel Storage Facility – a massive underground Navy fuel storage complex built during World War II in the hills above Pearl Harbor – leaked jet fuel into the groundwater that feeds drinking water wells serving military housing and nearby civilian communities. While the Red Hill crisis centered on petroleum contamination, subsequent investigation revealed PFAS contamination as well, from AFFF use at the facility and at nearby military installations.
The EPA's UCMR5 monitoring has added systematic data to what was already a charged situation. PFAS detections have been confirmed at water systems on Oahu, particularly in areas near military operations. The Hawaii DOH has conducted supplemental PFAS testing around known contamination sources.
Hawaii does not currently have state-specific PFAS MCLs. The state follows federal EPA standards, with the 2024 MCLs of 4 ppt for PFOA and PFOS applying to public water systems. Given the intensity of the Red Hill crisis, there has been public pressure to adopt stricter state standards, but as of early 2026, the state relies on federal limits.
The military footprint in Hawaii is enormous relative to the state's size, and PFAS contamination reflects that presence.
The Red Hill Bulk Fuel Storage Facility is the most infamous contamination site. In November 2021, a fuel leak contaminated the Navy's water system serving approximately 93,000 military personnel and family members. The crisis forced the shutdown of the Red Hill facility and triggered a massive remediation effort. While the primary contaminant was jet fuel (JP-5), PFAS from AFFF used at the facility and surrounding installations has been detected in the same groundwater zone. The Department of Defense agreed to permanently close and defuel Red Hill in 2022, and defueling was completed in 2024, but groundwater remediation continues.
Joint Base Pearl Harbor-Hickam has confirmed PFAS from AFFF use associated with flight line operations. The base's location above Oahu's primary aquifer system – the same system that Red Hill contaminated – makes this contamination geographically significant.
Marine Corps Base Hawaii (Kaneohe Bay) on the windward side of Oahu has been investigated for PFAS contamination. The base's flight operations and fire training activities involved AFFF use over many decades.
Schofield Barracks and Wheeler Army Airfield, located in central Oahu, are additional sites under PFAS investigation. These installations sit above the Schofield Plateau aquifer, which feeds drinking water wells for military and civilian communities.
On other islands, Pacific Missile Range Facility (PMRF) on Kauai has been flagged for PFAS assessment. The relative isolation of Kauai's water supply makes any contamination there a heightened concern.
The Department of Defense presence in Hawaii is pervasive, and the PFAS investigation covers installations across multiple islands. Our military bases page tracks each site's current status.
Hawaii's regulatory response to PFAS has been shaped by the Red Hill crisis, which elevated water contamination from a technical issue to a political one. The state legislature has held hearings, the governor has demanded federal accountability, and public trust in the military's stewardship of shared water resources has been severely damaged.
DOH has increased PFAS monitoring around military installations and has worked with the EPA on oversight of Red Hill remediation. The state's UCMR5 data provides additional baseline information for systems that were not previously tested for PFAS.
According to DOH's Safe Drinking Water Branch, private well use in Hawaii is less common than on the mainland – the majority of residents are served by public water systems. However, some rural communities on the Big Island, Maui, and Kauai do rely on private wells or small community systems that may not have been tested for PFAS.
The unique geology of Hawaii means that PFAS in groundwater behaves differently than on the mainland. The thin freshwater lenses on each island mean that contamination cannot be diluted by drawing from deeper or more distant sources. What enters the aquifer stays in the drinking water zone until it is treated or migrates to the ocean.
For a detailed look at PFAS science and how these compounds interact with water systems, see our PFAS guide.
Hawaii's island geography makes water quality a higher-stakes issue than in most states. There is no backup supply.
1. Check your ZIP code at the homepage to see available monitoring data for your water system. We compile UCMR5, DOH, and utility data for all islands. 2. If you are on Oahu – particularly in areas near Pearl Harbor, Red Hill, or central Oahu military installations – monitoring your water quality closely is important. The situation has improved since the Red Hill crisis, but remediation is ongoing. 3. A reverse osmosis filter provides the broadest protection against both PFAS and residual petroleum compounds. Our water filter guide covers systems rated for both contaminant classes. 4. Request a detailed water report for your address to see how your area's readings have changed since the Red Hill crisis and how they compare to federal standards.
Hawaii's water is a shared and limited resource. The Red Hill crisis demonstrated how quickly a contamination event can affect an entire island's supply. Check your specific location to see current data for your area.