Contaminants and rules in Hawaii water systems
15 different rules and contaminants appear in the past three years of violation records for Hawaii's 135 active public water systems. The tables show how many systems each one affected and how many of those violations are still unresolved. Most entries are monitoring, reporting, or notification lapses rather than confirmed contamination.
Inorganic Chemical
Naturally occurring or from fertilizer and industry. Each has a maximum contaminant level.
Disinfection Byproduct
Formed when chlorine reacts with organic matter in the water.
| Rule or contaminant | Code | Hawaii systems with violations, 3 yr | Share | In violation, latest quarter |
|---|---|---|---|---|
| Total Haloacetic Acids (HAA5) | 2456 | 1 | 1% | 0 |
| TTHM (Total Trihalomethanes) | 2950 | 1 | 1% | 0 |
Treatment Technique
Rules that require a process, such as corrosion control or disinfection, rather than a measured limit.
| Rule or contaminant | Code | Hawaii systems with violations, 3 yr | Share | In violation, latest quarter |
|---|---|---|---|---|
| Lead and Copper Rule (LCR) | 5000 | 6 | 4% | 6 |
| Interim Enhanced Surface Water Treatment Rule | 0300 | 1 | 1% | 0 |
Monitoring and Reporting
Administrative requirements. No direct health risk from the violation itself.
| Rule or contaminant | Code | Hawaii systems with violations, 3 yr | Share | In violation, latest quarter |
|---|---|---|---|---|
| Public Notification Rule | 7500 | 2 | 1% | 2 |
About this data
A system is counted once per rule if any of its violations in the past three years involved that rule, including monitoring and reporting lapses. In violation, latest quarter counts systems whose contaminant list for the latest official quarter in EPA's data, or new violations reported since, includes this entry. Share is of the 135 active Hawaii systems.
Source: the U.S. EPA's Enforcement and Compliance History Online system (ECHO), which publishes the federal Safe Drinking Water Information System. EPA's terms and values are shown as published. The Hawaii records are from EPA's data refresh of Oct 7, 2026; EPA refreshes this data quarterly, and states report to EPA with a lag of three to six months, so the newest violations may not appear yet. Retrieved from ECHO on Oct 11, 2026.