01The verdict: is Waiohinu-Naalehu water safe?
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).
Nothing over a legal limit
Every contaminant measured in Waiohinu-Naalehu's water is within its EPA limit, and no violations are unresolved.
See the testing ↓A clean compliance record
Waiohinu-Naalehu has no EPA violations on file — a stronger record than most systems its size.
See the record ↓Check back after the next refresh
EPA data updates on a rolling basis; we fold in new samples and violations every month.
Get alerts ↓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.
Waiohinu-Naalehu ranks #6 out of 64 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.
02What's in Waiohinu-Naalehu's water
Every contaminant flagged in Waiohinu-Naalehu, on one shared scale: distance to its own legal limit. The red line is the limit — anything past it is out of compliance, and the closer a bar gets, the less headroom the system has.
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 |
Cities ranked by 90th-percentile lead PF PFAS in Hawaii
Cities ranked by compounds detected Cu Copper in Hawaii
Cities ranked by 90th-percentile copper
03Waiohinu-Naalehu's ten-year track record
Each box is one year. A green check means no EPA violations; a numbered badge counts that year's violations — red if any were health-based, amber if they were monitoring or paperwork issues. No violations are on record for this water system.
All ten of the last ten years were clean — no EPA violations recorded for Waiohinu-Naalehu.
▼ Down 5 ppb since 2007. Latest reading: 0 ppb (2022) — 0% of the action level. Sampled at higher-risk homes (90th percentile).
04Where Waiohinu-Naalehu's water comes from
Waiohinu-Naalehu's drinking water is drawn from underground aquifers through wells.
Groundwater
Underground aquifers reached by wells — naturally filtered, but can carry minerals like arsenic and nitrate.
Local treatment
Groundwater generally needs less treatment — typically disinfection and, where needed, mineral removal.
1 system
1 water system, operated under local government ownership.
2,948 people
Residents served across Waiohinu-Naalehu's service area.
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.
| System name | PWSID | Population | Source |
|---|---|---|---|
| WAIOHINU-NAALEHU | HI0000108 | 2,948 | Groundwater |
Water bodies near Waiohinu-Naalehu
These water bodies shape the regional watershed and can indirectly affect groundwater quality.
05How Waiohinu-Naalehu compares
Scores for nearby Hawaii cities on one line, with the average marked.
dashed line = Hawaii average (92/100)
Waiohinu-Naalehu scores 98.5/100 — above the Hawaii average of 92/100. It outscores 10 of 10 nearby cities. Full Hawaii rankings →
91.1 / 100AWaipahu-Ewa-Waianae, HI
92.8 / 100AWailuku, HI
91.4 / 100APearl Harbor, HI
94.8 / 100AMililani Bws, HI
97.5 / 100ASchofield Barracks, HI
91.8 / 100
Compare all cities in the county — grades, violations, and contaminant data side by side.→
06What to do at home
Steps matched to what testing actually found in Waiohinu-Naalehu's water — not generic advice.
A basic carbon filter still helps
Waiohinu-Naalehu's water meets federal standards, but a simple carbon filter improves taste and adds a margin of safety against short-term issues.
Compare tested filters →Read your utility's annual report
Every utility must publish a yearly Consumer Confidence Report with its own testing results. It pairs well with the independent data on this page.
How to read a CCR →Watch for Waiohinu-Naalehu alerts
We refresh EPA data monthly and surface new violations, advisories, and boil-water notices for your county on this page.
All water alerts →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 64 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 64 cities in Hawaii (better than 91% of state cities) and #40 out of 15382 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.