Hawaii Water Quality
Drinking water data for all 4 counties.
Avg SDWIS Compliance Index
78.6
Most Common Five-Year SDWIS Compliance Band
A
Counties with Data
4
of 4 total
County water atlas
Hawaii water signals by county
A state-level 2.5D view across drinking-water compliance, watershed impairment, monitoring density, and streamflow snapshot context. Pin any county, switch layers, then use the lens controls to compare index ranges, recorded violation rates, or impaired watersheds without leaving the page.
Counties
4
Avg SDWIS index
78.6
Watersheds
0
ATTAINS counties
Monitoring
4
4 fresh USGS snapshots
State atlas layers combine EPA SDWIS health-based violations, EPA ATTAINS 303(d) impairment assessments, EPA Water Quality Portal monitoring sites, and representative USGS NWIS streamflow gauges. Streamflow values appear only for fresh pipeline snapshots, not as a continuously updated stream. County pages include the observation time and year.
Multi-source coverage in Hawaii
Beyond Drinking Water
EPA SDWIS
4/ 4
counties with drinking-water compliance data
3 health violations statewide (5yr)
EPA ATTAINS
—
No §303(d) assessments yet for Hawaii
EPA WQP
550
monitoring sites across 4 counties
267,201 total readings (5yr window)
USGS NWIS
4
counties with a fresh pipeline snapshot
1 above3 below
State atlas notes
What stands out in Hawaii
County water quality is not one number. The strongest read comes from comparing drinking-water compliance against watershed impairment, monitoring density, and streamflow context. Use these signals as a starting point, then open any county profile for source-level detail.
Compliance spread
Kauai County has the highest value in the published state SDWIS Compliance Index table at 86.2/100, while Hawaii County has the lowest at 70.3/100. That is a 15.9 point gap inside one state.
Zero health violations
2
3+ health violations
0
Lowest flow reads
Highest fresh streamflow pipeline snapshots: Honolulu County (317%, observation 2026), Kauai County (58%, observation 2026), Hawaii County (16%, observation 2026). These are source-data observations, not household tap-water conclusions.
All Hawaii Counties
| County | SDWIS Compliance Index |
|---|---|
| Kauai County | 86.2 |
| Maui County | 86.2 |
| Honolulu County | 71.9 |
| Hawaii County | 70.3 |
Frequently Asked Questions
Which Hawaii county has the highest SDWIS Compliance Index?
What does the Five-Year SDWIS Compliance Band mean?
Which USGS streamflow records are shown across Hawaii?
Where can Hawaii residents find current official information?
What does Water Quality Portal monitoring volume show in Hawaii?
Data Sources
Drinking-water compliance data from the EPA Safe Drinking Water Information System (SDWIS) via the ECHO enforcement database. The WaterByCounty SDWIS Compliance Index reflects the recorded rate and is not an EPA score.
Disclaimer: This data is informational only. It is not health, legal, or professional advice. For concerns about your specific water supply, contact your local water utility.