The public water system serving Lihue-Kapaa, Kauai County, reports multiple detections of chromium-6 (hexavalent chromium) in its surface water supply based on EPA monitoring data.
What is the difference between trivalent chromium and hexavalent chromium, and why can’t total chromium levels alone answer my concerns?
Chromium occurs in several forms, with trivalent chromium (Cr(III)) and hexavalent chromium (Cr(VI)) being the most common in water sources. Total chromium measurements sum all forms but do not specify which oxidation state dominates. This distinction matters because Cr(VI) can behave differently in water chemistry and treatment compared to Cr(III). For example, Cr(III) is an essential trace nutrient in small amounts, whereas Cr(VI) has different chemical properties that influence taste or staining potential. Since the Lihue-Kapaa system monitoring reports both total chromium and chromium-6 levels separately, understanding these differences helps in assessing the water condition more precisely.
How can the oxidation state of chromium change from the water source to my household tap?
Chromium’s oxidation state can shift due to chemical reactions occurring between the source water, treatment processes, distribution system, and household plumbing materials. For instance, surface water might contain chromium primarily as hexavalent chromium due to oxidation conditions, but it can convert to the trivalent form or other states as it passes through the water system. Conversely, changes in pH or disinfectant presence in distribution can impact chromium speciation before reaching your tap. Because these transformations are dynamic, local government sampling detects chromium-6 at the distribution system but does not measure exact tap-level values for individual homes.
What do terms like 'detected', 'median', and 'range' mean in the chromium-6 sampling record for Lihue-Kapaa?
The EPA’s unregulated contaminant monitoring rule (UCMR3) results are based on multiple water samples taken across the public water system. 'Detected' means the constituent was measured above the analytical reporting level, not that it poses a health or regulatory violation. For chromium-6 in Lihue-Kapaa, 61 out of 63 samples detected chromium-6 above 0.03 micrograms per liter (µg/L). The highest concentration measured was 6.8 µg/L, and the median of detected values was 2.4 µg/L. These figures represent the range of levels found but do not equate to findings about individual wells or taps or indicate that the water exceeds any federal limit. The total chromium maximum contaminant level (MCL) set federally is 100 µg/L, which is significantly higher than detected chromium-6 values in this system.
Why did California set its own 10 µg/L limit for chromium-6, and what does that mean for Kauai residents?
California established a public health goal of 0.02 µg/L and a regulatory maximum of 10 µg/L for hexavalent chromium in drinking water after evaluating studies suggesting potential health risks at higher levels. This standard is specific to California and reflects that state’s policy decisions, regulatory framework, and risk assessments. Kauai County and the EPA do not have a federal maximum contaminant level (MCL) specifically for chromium-6. Because the highest chromium-6 concentration detected in the Lihue-Kapaa system was below 7 µg/L, it is below California’s regulatory limit. However, residents elsewhere should note that differing state standards do not imply unsafe conditions but represent different precautionary approaches. Testing your own tap water remains the only way to understand chromium-6 concentration at your household.
How does the C-Series Chromium-6 Filter address chromium-6 in residential water?
The C-Series Chromium-6 Filter uses targeted technology designed to reduce or neutralize hexavalent chromium from household water supplies. It functions to treat chromium-6 specifically, improving water quality where levels are a concern based on testing. The system ships ready to configure for residential settings and provides an option for homeowners evaluating treatment classes to address hexavalent chromium. Since individual water chemistry and levels vary, testing your water before selecting treatment confirms appropriateness.
What should I NOT conclude from the regional chromium-6 data?
Area sampling results reflect the public water system’s average water quality and cannot predict your household’s specific water condition. Detection of chromium-6 does not indicate regulatory violation or unsafe water according to EPA records. The data do not specify concentrations at individual taps, nor do they provide a basis for health risk conclusions without further context. Homeowners considering water treatment should base decisions on their own water tests and consult resources on effective options like the C-Series Chromium-6 Filter.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2015-07-31. These figures describe the public water system's record, not the plumbing inside any individual building.
On record: EPA UCMR3 monitoring (2013-2015) for Lihue-Kapaa (HI0000400), HI: 126 results across 2 listed contaminants, 119 detections above the reporting level; no federal MCL for hexavalent chromium; total chromium MCL 100 ug/L