Is Kahuku, HI Tap Water Safe to Drink?
Graded A-, with 1 unresolved violation on record. See what was cited — and what it means for your tap. What to do next ↓
85.9/100
waterverge.com Kahuku, HI — Water Quality Report
Kahuku's drinking water received a grade of A- (85.9 out of 100), indicating good water quality. The city's 1 water system serves approximately 2,730 residents using groundwater.
Lead levels were measured at 0.0 ppb (90th percentile), well within EPA limits. This system has not yet been tested for PFAS under the EPA UCMR 5 program.
The system has 1 violation on record, including 0 health-based violations. 1 remains unresolved.
What to know about Kahuku's water
Kahuku ranks #56 out of 66 cities in Hawaii for water quality, placing it among the lowest-rated in the state.
Kahuku relies on groundwater, which is generally less vulnerable to surface contamination but can be affected by naturally occurring minerals like arsenic and nitrate, as well as agricultural and industrial runoff.
As a small community water system, Kahuku may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
Water quality score
See methodology →Is Kahuku, HI water safe to drink?
Kahuku's tap water meets most EPA standards but has areas that warrant attention. With a grade of A- (85.9/100), some contaminant levels or compliance issues suggest that residents may benefit from additional filtration. The city's 1 water system serves approximately 2,730 residents using groundwater (wells).
Recent water quality updates for Kahuku
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into Kahuku's water quality assessment. Grade: A- (85.9/100).
Federal disaster declaration (FEMA DR-3529). Hurricane event — may have impacted local water infrastructure.
Federal disaster declaration (FEMA DR-3404). Hurricane event — may have impacted local water infrastructure.
Contaminants: Lead and Copper Rule.
Key contaminant findings
Based on the most recent EPA sampling data for Kahuku's water supply.
Well within EPA limits.
Violation history
Kahuku's water system has 1 total violation on record, including 0 health-based violations. 1 remain unresolved.
Flood & environmental risk
Honolulu County has experienced 9 federally declared disasters since 1974. Flooding and severe storms can overwhelm water treatment plants, cause sewage overflows, and introduce agricultural runoff, bacteria, and sediment into drinking water supplies. Local water sources include N. Halawa Str Nr Honolulu, Oahu, N. Halawa Str Nr Quar. Stn. At Halawa, Oahu, South Halawa Stream Nr H-3 Freeway, Oahu, Moanalua Stream Nr Kaneohe, Oahu, Kalihi Str Nr Honolulu, Oahu.
Where does Kahuku's water come from?
Kahuku's drinking water comes from groundwater (wells), supplied by 1 water system serving approximately 2,730 people. Groundwater is generally less susceptible to surface contamination but can contain naturally occurring contaminants like arsenic, radon, and nitrate. Nearby water bodies include N. Halawa Str Nr Honolulu, Oahu (river), N. Halawa Str Nr Quar. Stn. At Halawa, Oahu (river), South Halawa Stream Nr H-3 Freeway, Oahu (river), Moanalua Stream Nr Kaneohe, Oahu (river), Kalihi Str Nr Honolulu, Oahu (river).
What Kahuku residents can do
Your water utility is required to publish an annual Consumer Confidence Report (CCR) with detailed testing results. Ask for the latest copy or check your utility's website.
Kahuku's area has a history of flooding. After severe weather, watch for boil water advisories from your local utility.
Data: EPA SDWIS, UCMR 5 (PFAS), FEMA, NOAA. Last updated May 2026.
Top contaminants to know
View all ↓Violation summary
Violations & advisories
Flood & disaster history
Honolulu County has experienced 9 federally declared disasters since 1974. Flooding and severe weather can compromise water treatment infrastructure and introduce contaminants into drinking water supplies.
Full contaminants report
| Contaminant | Detected Level | EPA Limit | Unit | Category | Status |
|---|---|---|---|---|---|
| Lead (90th percentile) LeadHeavy Metal A toxic heavy metal that can leach into drinking water from older pipes, solder, and fixtures. No amount of lead in water is considered safe. Health EffectsBrain and nervous system damage in children, kidney damage, high blood pressure, and reproductive problems in adults. EPA Limit15 ppb action level Common SourcesCorrosion of lead pipes, lead solder, brass faucets, and household plumbing. | 0.0 | 15 | ppb | Inorganic | Safe |
Lead level trend (90th percentile)
See how Kahuku compares by contaminant
Explore where Kahuku ranks among all Hawaii cities for specific contaminants.
Water source & infrastructure
Where Kahuku's water comes from
Kahuku's drinking water is drawn from underground aquifers through wells.
Groundwater is naturally filtered through rock and soil layers, generally requiring less treatment than surface water. However, it can contain naturally occurring contaminants like arsenic, radon, and minerals.
Agricultural activity, septic systems, and industrial operations near well fields can introduce nitrates, pesticides, and volatile organic compounds.
The system is operated by local government ownership and serves approximately 2,730 people through 1 water system.
Water bodies near Kahuku
Kahuku is located near 5 notable water bodies. These water bodies contribute to the regional watershed and may indirectly affect groundwater quality.
Water systems serving Kahuku
| System Name | PWSID | Population | Source |
|---|---|---|---|
| KAHUKU | HI0000365 | 2,730 | GW |
How Kahuku compares
Full Hawaii rankings →Kahuku's score of 85.9/100 is below the average of 92/100 among major Hawaii cities. It outscores 1 of 10 nearby cities. 9 of 10 nearby cities score higher.
Nearby cities
View Hawaii rankings →About Kahuku, HI
Wikipedia →Honolulu is the capital and most populous city of the U.S. state of Hawaii, located in the Pacific Ocean. It is the county seat of the consolidated City and County of Honolulu, situated along the southeast coast of the island of Oʻahu. The population of Honolulu was 350,964 at the 2020 census, dropping to an estimated 344,967 by 2024. The Urban Honolulu metropolitan area had an estimated population of just under 1 million residents in 2024 and is the 56th-largest metropolitan area in the nation.
Learn more about your water
Guides and resources related to Kahuku's water quality findings.
Explore water quality across Honolulu
Frequently asked questions
Is Kahuku, HI tap water safe to drink?
Kahuku's water quality earned a grade of A- (85.9/100). The water generally meets EPA standards and is considered safe for consumption. The city ranks #56 out of 66 cities tested in Hawaii.
What contaminants are in Kahuku's water?
Lead was measured at 0.0 ppb (90th percentile). 1 violation is on record.
How is Kahuku's water quality grade calculated?
The grade is based on four factors: violation history (40%), lead and copper levels (25%), PFAS contamination (25%), and regulatory compliance (10%). The score is also adjusted based on how complete the available data is. See our methodology page for full details.
Do I need a water filter in Kahuku?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Kahuku's water come from?
Kahuku's water is sourced from Groundwater. The city has 1 water system serving approximately 2,730 residents.
Is Kahuku's groundwater at risk of contamination?
Kahuku uses groundwater, which can be affected by naturally occurring contaminants like arsenic, radon, and nitrate, as well as agricultural runoff and industrial activity. The system has 1 violation on record that may relate to groundwater quality. Groundwater systems are generally less susceptible to surface contamination but should be monitored for emerging contaminants like PFAS.
How does Kahuku's water compare to other cities?
Kahuku ranks #56 out of 66 cities in Hawaii (better than 15% of state cities) and #5026 out of 15744 cities nationally (68th percentile). The grade of A- reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.
Does Kahuku's small water system affect quality?
Kahuku's system serves approximately 2,730 residents. Small community water systems (under 3,300 people) may have fewer financial resources for infrastructure upgrades and advanced treatment technologies. However, they are held to the same EPA drinking water standards as larger systems. This system has 1 violation on record.