Is Waiohinu-Naalehu, HI Tap Water Safe to Drink?
Graded A+ with no contaminants above EPA limits. Here's everything we tested and how Waiohinu-Naalehu ranks. What to do next ↓
98.5/100
waterverge.com Waiohinu-Naalehu, HI — Water Quality Report
Waiohinu-Naalehu's drinking water received a grade of A+ (98.5 out of 100), indicating excellent water quality. The city's 1 water system serves approximately 2,948 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.
No violations are on record for this water system.
What to know about Waiohinu-Naalehu's water
Waiohinu-Naalehu ranks #6 out of 66 cities in Hawaii for water quality, placing it one of the best in the state.
Waiohinu-Naalehu 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, Waiohinu-Naalehu may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
Waiohinu-Naalehu has a clean compliance record with no violations on file, reflecting strong operational practices.
Water quality score
See methodology →Is Waiohinu-Naalehu, HI water safe to drink?
Based on EPA testing data, Waiohinu-Naalehu's tap water is generally safe to drink. The water system earned a grade of A+ (98.5/100), meeting federal drinking water standards across key contaminant categories. The city's 1 water system serves approximately 2,948 residents using groundwater (wells).
Recent water quality updates for Waiohinu-Naalehu
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into Waiohinu-Naalehu's water quality assessment. Grade: A+ (98.5/100).
Key contaminant findings
Based on the most recent EPA sampling data for Waiohinu-Naalehu's water supply.
Well within EPA limits.
Where does Waiohinu-Naalehu's water come from?
Waiohinu-Naalehu's drinking water comes from groundwater (wells), supplied by 1 water system serving approximately 2,948 people. Groundwater is generally less susceptible to surface contamination but can contain naturally occurring contaminants like arsenic, radon, and nitrate. Nearby water bodies include Wailuku River At Piihonua (river), Honolii Stream Nr Papaikou (river).
What Waiohinu-Naalehu 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.
Data: EPA SDWIS, UCMR 5 (PFAS), FEMA, NOAA. Last updated May 2026.
Top contaminants to know
View all ↓Violations & advisories
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 Waiohinu-Naalehu compares by contaminant
Explore where Waiohinu-Naalehu ranks among all Hawaii cities for specific contaminants.
Water source & infrastructure
Where Waiohinu-Naalehu's water comes from
Waiohinu-Naalehu'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 2,948 people through 1 water system.
Water bodies near Waiohinu-Naalehu
Waiohinu-Naalehu is located near 2 notable water bodies. These water bodies contribute to the regional watershed and may indirectly affect groundwater quality.
Water systems serving Waiohinu-Naalehu
| System Name | PWSID | Population | Source |
|---|---|---|---|
| WAIOHINU-NAALEHU | HI0000108 | 2,948 | GW |
How Waiohinu-Naalehu compares
Full Hawaii rankings →Waiohinu-Naalehu's score of 98.5/100 is above the average of 92/100 among major Hawaii cities. It outscores 10 of 10 nearby cities.
Nearby cities
View Hawaii rankings →About Waiohinu-Naalehu, HI
Wikipedia →Hilo is the largest settlement in and the county seat of Hawaiʻi County, Hawaii, United States, which encompasses the Island of Hawaiʻi, and is a census-designated place (CDP). The population was 44,186 according to the 2020 census. It is the fourth-largest settlement in the state of Hawaiʻi, the largest settlement in the state outside of Oahu, and the largest settlement in the state outside of the Greater Honolulu Area.
Learn more about your water
Guides and resources related to Waiohinu-Naalehu's water quality findings.
Explore water quality across Hawaii
Frequently asked questions
Is Waiohinu-Naalehu, HI tap water safe to drink?
Waiohinu-Naalehu's water quality earned a grade of A+ (98.5/100). The water generally meets EPA standards and is considered safe for consumption. The city ranks #6 out of 66 cities tested in Hawaii.
What contaminants are in Waiohinu-Naalehu's water?
Lead was measured at 0.0 ppb (90th percentile). No violations on record.
How is Waiohinu-Naalehu'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 Waiohinu-Naalehu?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Waiohinu-Naalehu's water come from?
Waiohinu-Naalehu's water is sourced from Groundwater. The city has 1 water system serving approximately 2,948 residents.
Is Waiohinu-Naalehu's groundwater at risk of contamination?
Waiohinu-Naalehu uses groundwater, which can be affected by naturally occurring contaminants like arsenic, radon, and nitrate, as well as agricultural runoff and industrial activity. Current testing shows the groundwater meets EPA standards. Groundwater systems are generally less susceptible to surface contamination but should be monitored for emerging contaminants like PFAS.
How does Waiohinu-Naalehu's water compare to other cities?
Waiohinu-Naalehu ranks #6 out of 66 cities in Hawaii (better than 91% of state cities) and #40 out of 15744 cities nationally (100th percentile). The grade of A+ reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.
Does Waiohinu-Naalehu's small water system affect quality?
Waiohinu-Naalehu's system serves approximately 2,948 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 maintained a clean compliance record.