Hawaii Water Quality Report: 16 Violations Across 137 ZIPs
145 water systems · 137 ZIP codes · 16 violations · Updated 2026-05-31
Data: EPA Safe Drinking Water Information System (SDWIS), EPA ECHO Last verified: 2026-05-31
City Water Quality Map: Hawaii
Each circle represents a city. Size indicates population, color indicates water quality grade. Tap a circle for details.
Cities with Most Violations in Hawaii
| # | City | Grade | Violations | Systems | Population | |
|---|---|---|---|---|---|---|
| 1 | Hilo | B | 4 | 5 | 91,649 | Details → |
| 2 | Maunaloa | B | 4 | 3 | 1,580 | Details → |
| 3 | Kaneohe | B | 3 | 1 | 16,300 | Details → |
| 4 | Schofield Barracks | A | 1 | 4 | 56,948 | Details → |
| 5 | Lanai City | A | 1 | 1 | 3,200 | Details → |
| 6 | Kualapuu | A | 1 | 1 | 500 | Details → |
| 7 | Holualoa | A | 1 | 1 | 250 | Details → |
| 8 | Kalaupapa | A | 1 | 1 | 110 | Details → |
Cities with Best Water Quality in Hawaii
| # | City | Grade | Score | Systems | Population |
|---|---|---|---|---|---|
| 1 | Makawao | A | 95/100 | 4 | 32,100 |
| 2 | Kula | A | 95/100 | 4 | 12,488 |
| 3 | Lahaina | A | 90/100 | 2 | 20,107 |
| 4 | Kaunakakai | A | 90/100 | 3 | 6,655 |
| 5 | Hoolehua | A | 88/100 | 1 | 2,400 |
| 6 | Papaikou | A | 88/100 | 1 | 2,203 |
| 7 | Pepeekeo | A | 88/100 | 2 | 1,510 |
| 8 | Laupahoehoe | A | 88/100 | 1 | 1,169 |
| 9 | Waikoloa | A | 87/100 | 4 | 25,616 |
| 10 | Kalaheo | A | 87/100 | 2 | 12,920 |
Most Common Contaminants in Hawaii
| Contaminant | Category | Violations | ZIPs Affected | Health Risk |
|---|---|---|---|---|
| Stage 1 DBP Rule | Treatment Technique | 11 | 7 | No |
| Fecal Coliform | Microbiological | 2 | 2 | No |
| Stage 2 DBP Rule | Treatment Technique | 1 | 1 | Yes |
| Surface Water Treatment Rule | Treatment Technique | 1 | 1 | No |
| Lead and Copper Rule | Treatment Technique | 1 | 1 | No |
Water Quality Overview
Hawaii has 145 community water systems serving approximately 3,629,045 people across 137 ZIP codes. These systems have accumulated 16 EPA violations, including 1 health-based violations.
Health-based violations account for 6% of all violations in Hawaii. These violations indicate contaminant levels that may pose direct risks to human health, as opposed to monitoring or reporting failures.
Violation Breakdown
| Violation Type | Count | Percentage |
|---|---|---|
| Health-based | 1 | 6.3% |
| Monitoring/Reporting | 15 | 93.8% |
| Total | 16 | 100% |
Health-based violations indicate contaminant levels exceeding EPA Maximum Contaminant Levels (MCLs). Monitoring violations indicate failures to test or report — these do not necessarily mean unsafe water, but they mean the water was not properly verified.
Cities with Most Violations
The following cities in Hawaii have the highest number of EPA violations:
| Rank | City | Grade | Violations | Water Systems | Population |
|---|---|---|---|---|---|
| 1 | Hilo | B | 4 | 5 | 91,649 |
| 2 | Maunaloa | B | 4 | 3 | 1,580 |
| 3 | Kaneohe | B | 3 | 1 | 16,300 |
| 4 | Schofield Barracks | A | 1 | 4 | 56,948 |
| 5 | Lanai City | A | 1 | 1 | 3,200 |
| 6 | Kualapuu | A | 1 | 1 | 500 |
| 7 | Holualoa | A | 1 | 1 | 250 |
| 8 | Kalaupapa | A | 1 | 1 | 110 |
Violation counts are cumulative across all water systems serving each city. Higher counts may reflect larger systems with more monitoring requirements, not necessarily worse water quality.
Cities with Best Water Quality
These Hawaii cities maintain Grade A water with zero violations:
| Rank | City | Grade | Score | Water Systems | Population |
|---|---|---|---|---|---|
| 1 | Makawao | A | 95/100 | 4 | 32,100 |
| 2 | Kula | A | 95/100 | 4 | 12,488 |
| 3 | Lahaina | A | 90/100 | 2 | 20,107 |
| 4 | Kaunakakai | A | 90/100 | 3 | 6,655 |
| 5 | Hoolehua | A | 88/100 | 1 | 2,400 |
| 6 | Papaikou | A | 88/100 | 1 | 2,203 |
| 7 | Pepeekeo | A | 88/100 | 2 | 1,510 |
| 8 | Laupahoehoe | A | 88/100 | 1 | 1,169 |
| 9 | Waikoloa | A | 87/100 | 4 | 25,616 |
| 10 | Kalaheo | A | 87/100 | 2 | 12,920 |
Most Common Contaminants
The following contaminants have caused the most violations across Hawaii water systems:
| Contaminant | Category | Violations | ZIPs Affected | Health-Based |
|---|---|---|---|---|
| Stage 1 DBP Rule | Treatment Technique | 11 | 7 | No |
| Fecal Coliform | Microbiological | 2 | 2 | No |
| Stage 2 DBP Rule | Treatment Technique | 1 | 1 | Yes |
| Surface Water Treatment Rule | Treatment Technique | 1 | 1 | No |
| Lead and Copper Rule | Treatment Technique | 1 | 1 | No |
How to Check Your Water in Hawaii
Enter your ZIP code on ZipCheckup for detailed water system data including contaminant levels, violation history, and safety scores
Request your CCR — every water utility must provide an annual Consumer Confidence Report
Get a home test — certified kits ($20-$50) or professional lab tests ($150-$400)
Consider filtration — NSF-certified filters can address specific contaminants found in your area
EPA Enforcement
The EPA and state regulators have taken 231 enforcement actions against water systems in Hawaii. Enforcement actions range from compliance assistance to formal orders and penalties.
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Enforcement: EPA ECHO
Updated daily.
Understanding water quality grades
ZipCheckup grades water systems from A to F based on EPA violation history, contaminant levels, and system compliance. Grade A means few or no violations; Grade F indicates persistent or serious issues. Grades are calculated per ZIP code and aggregated at the city, county, and state level.
Wondering about your tap water?
Water quality varies by ZIP code. Enter yours to see contaminant data, violations, and filtration recommendations specific to your area.
Check Your ZIP Code Water Quality →Frequently Asked Questions
Is the tap water safe to drink in Hawaii?
Hawaii has 145 community water systems with 16 recorded EPA violations, including 1 health-based. Water quality varies by city and ZIP code — check your specific location for detailed results.
How many water violations does Hawaii have?
Hawaii has 16 total EPA violations across 137 ZIP codes. 1 are health-based violations that indicate contaminant levels potentially harmful to human health. The remainder are monitoring or reporting violations.
Which city in Hawaii has the worst water quality?
Hilo, HI has the most EPA violations among major cities in Hawaii with 4 recorded violations. Check individual ZIP codes for the most accurate picture of your local water quality.
Which city in Hawaii has the best water quality?
Makawao, HI ranks among the best for water quality in Hawaii with a grade of A. Multiple cities in Hawaii maintain strong EPA compliance records.
What contaminants are found in Hawaii drinking water?
Hawaii water systems are monitored for over 90 EPA-regulated contaminants including lead, copper, nitrates, disinfection byproducts, and bacteria. The most common violations vary by region — check your ZIP code for contaminant-specific data.