Every year, Hawaii Water’s Water Quality Lab performs thousands of tests to monitor the quality of our water. If any contaminants are found, they are listed in the annual water quality report. However, most of the contaminants we test for are not found, so they are not listed in the water quality report.
The below table lists all of the contaminants that the Hawaii Department of Public Health (HDPH) requires Hawaii Water to test for, along with their maximum containment level (MCL). If you have any questions about this table or about the quality of your water, please contact the Hawaii Water Customer Center.
**Get more information on EPA’s adoption of MCLs for certain PFAS. No Hawaii Water drinking water sources are currently impacted by the new regulation.**
Contaminants Regulated by the Safe Drinking Water Branch (effective 3/4/09)
Microbiological
Total Coliform Bacteria:
- 40 or more samples per month:
No more than 5.0% of the samples may be total coliform positive - Less than 40 samples/month:
No more than 1 sample/month may be total coliform positive
Fecal Coliform or E. coli Bacteria:
An acute violation occurs when:
- A total coliform positive routine is followed by a fecal coliform or E. coli positive repeat, OR
- A fecal coliform or E. coli positive routine is followed by a total coliform positive repeat
| Inorganic Chemicals | |
| Contaminant | MCL (mg/l) |
| Arsenic | 0.01 |
| Asbestos | 7 million fibers per liter |
| Barium | 2. |
| Cadmium | 0.005 |
| Chromium | 0.1 |
| Copper (Action Level) | 1.3 |
| Lead (Action Level) | 0.015 |
| Mercury | 0.002 |
| Nitrate (as Nitrogen) | 10. |
| Nitrite (as Nitrogen) | 1. |
| Total Nitrate & Nitrite (as Nitrogen) | 10. |
| Selenium | 0.05 |
| Fluoride | 4.0 |
| Antimony | 0.006 |
| Beryllium | 0.004 |
| Cyanide (as free Cyanide) | 0.2 |
| Thallium | 0.002 |
| Disinfection Byproducts | |
| Contaminant | MCL (mg/l) |
| (only Subpart H & P systems with population >10,000 until 1/1/04) | |
| Total trihalomethanes (sum of chloroform, bromoform, bromodichloromethane, dibromochloromethane) |
0.080 |
| Total Haloacetic Acids (sum of mono-, di-, trichloroacetic acids and mono- and dibromoacetic acids. |
0.060 |
| Chlorite (usually formed under ClO2 use) | 1.0 |
| Bromate (brominated waters using ozone) | 0.010 |
| Radionuclides | |
| Contaminant | MCL (mg/l) |
| (applies to all community water systems) | |
| Gross alpha particle | 15 pCi/l |
| Combined radium 226/228 | 5 pCi/l |
| Uranium | 30 µg/l |
| Beta/photon emitters | 4 mrem/yr (applies only to systems using surface water with populations > 100,000) |
| Organic Chemicals | ||||
| Contaminant | MCL (mg/l) | Contaminant | MCL (mg/l) | |
| Volatile Organic Chemicals | ||||
| Benzene | 0.005 | Styrene | 0.1 | |
| Carbon Tetrachloride | 0.005 | Tetrachloroethylene | 0.005 | |
| Chlorobenzene | 0.1 | Toluene | 1. | |
| o-Dichlorobenzene | 0.6 | 1,1,1-Trichloroethane | 0.2 | |
| para-Dichlorobenzene | 0.075 | Trichloroethylene | 0.005 | |
| 1,2-Dichloroethane | 0.005 | TCP (1,2,3-Trichloropropane) | 0.0006 | |
| 1,1-Dichloroethylene | 0.007 | Vinyl Chloride | 0.002 | |
| cis-1,2-Dichloroethylene | 0.07 | Xylenes (total) | 10. | |
| trans-1,2-Dichloroethylene | 0.1 | Dichloromethane | 0.005 | |
| DCP (1,2-Dichloropropane) | 0.005 | 1,2,4-Trichlorobenzene | 0.07 | |
| Ethylbenzene | 0.7 | 1,1,2-Trichloroethane | 0.005 | |
| Synthetic Organic Chemicals | ||||
| Contaminant | MCL (mg/l) | Contaminant | MCL (mg/l) | |
| Alachlor | 0.002 | Dalapon | 0.2 | |
| Atrazine | 0.003 | Di(2-ethylhexyl) adipate | 0.4 | |
| Carbofuran | 0.04 | Di(2-ethylhexyl) phthalate | 0.006 | |
| Chlordane | 0.002 | Dinoseb | 0.007 | |
| DBCP (Dibromochloropropane) | 0.00004 | Diquat | 0.02 | |
| 2,4-D | 0.07 | Endothall | 0.1 | |
| EDB (Ethylene Dibromide) | 0.00004 | Endrin | 0.002 | |
| Heptachlor | 0.0004 | Glyphosate | 0.7 | |
| Heptachlor Epoxide | 0.0002 | Hexachlorobenzene | 0.001 | |
| Lindane | 0.0002 | Hexachlorocyclopentadiene | 0.05 | |
| Methoxychlor | 0.04 | Oxamyl (Vydate) | 0.2 | |
| Pentachlorophenol | 0.001 | Picloram | 0.5 | |
| Toxaphene | 0.003 | Simazine | 0.004 | |
| 2,4,5-TP (Silvex) | 0.05 | 2,3,7,8-TCDD (Dioxin) | 3 X 10 -8 | |
| Benzo(a)pyrene | 0.0002 | |||