In Wailuku, Maui County, many households notice their tap water occasionally tastes metallic or has a faint chemical aftertaste. These are common sensory clues that chromium-6 (also known as hexavalent chromium or chromium(VI)) may be present in the water supply, as government sampling has found.
1. How Ion Exchange and Reverse Osmosis Differ in Their Interaction with Chromium(VI)
Ion Exchange Targets Chromium(VI) Specifically
Ion exchange equipment uses resin beads that attract and hold chromium-6 ions from the water, exchanging them for less problematic ions. This process focuses on chromium(VI), aiming to reduce its concentration directly within the treated water volume.
Reverse Osmosis Filters Multiple Constituents
Reverse osmosis pushes water through a membrane that blocks many dissolved particles, including chromium-6. It reduces overall dissolved solids along with chromium(VI), offering a broad spectrum filtration effect.
Efficiency and Daily Demand
Ion exchange systems typically manage larger daily water volumes efficiently, making them suitable when chromium(VI) presence is known and daily water use is high. Reverse osmosis, while thorough, produces less filtered water per day and may be better for low-volume needs or point-of-use treatment.
2. Why a Total Chromium Measurement Doesn’t Tell the Whole Story
Hexavalent Versus Trivalent Chromium
Total chromium measurements include chromium in multiple oxidation states, primarily chromium(III) and chromium(VI). Chromium(III) is an essential nutrient, while chromium-6 is the form of regulatory and public interest.
The Wailuku Record Highlights Chromium(VI) Separately
Government sampling for Wailuku consistently detected chromium-6 at median 1.2 micrograms per liter (µg/L or parts per billion), distinct from total chromium median at 1.3 µg/L. This differentiation shows chromium(VI) forms a major portion of the total chromium present in the supply.
Testing Your Own Water
Only a specific laboratory test for chromium-6 can clarify its presence at your tap, as total chromium results alone cannot specify chromium(VI) levels.
3. Working Through the Record’s Median and Range for Home Use
Median Chromium(VI) Levels in Wailuku
The recorded median detection of chromium-6 in Wailuku’s public water system was 1.2 µg/L, with the highest single measurement at 2.9 µg/L. These numbers reflect concentrations found throughout the supply—not measurements at individual homes.
What This Means for Your Household
You should understand that these values indicate what has been found in the municipal water source and distribution system from 2013 to 2015. Your home's specific chromium-6 level may be different and requires individual testing to confirm.
No Regulatory Maximum Contaminant Level for Chromium(VI)
While total chromium has a federal maximum contaminant level at 100 µg/L, no federal limit exists specifically for chromium-6. The detections in Wailuku are well below total chromium limits and have no health-based violations recorded.
4. What to Record Before Seeking Equipment Guidance
Water Source and Testing History
Note that Wailuku’s municipal system uses surface water supply with no health-based chromium-6 violations. Having your own water tested for chromium-6 concentration is essential.
Household Water Usage
Write down your average daily water consumption and peak usage times; this will help in choosing equipment capacity aligned with household demand.
Current Water Quality Characteristics
Document any known concentrations of chromium-6 or total chromium from your last lab report, along with other relevant water chemistry details like pH and total dissolved solids, if known.
5. Household Signs That Are and Are Not Indicative of Chromium(VI)
Signs Possibly Related to Chromium-6
- Metallic or chemical taste at the tap
- Unusual staining on fixtures or laundry
Signs Not Specifically Tied to Chromium(VI)
- Cloudy or turbid water (often caused by sediment)
- General hardness or scaling (commonly due to calcium or magnesium)
- Odors unrelated to metallic or chemical tastes
When considering treatment options for chromium(VI), such symptoms should be interpreted cautiously and confirmed with proper water testing.
The public water system record from the EPA for Wailuku, Maui County covers chromium-6 monitoring between May 2014 and February 2015 and includes 87 detections all above the reporting level but below any health-based limits. For detailed government data, consult the EPA’s database of unregulated contaminant monitoring.
Products like the Fleck Chromium-6 Filter ship ready to configure and offer ion exchange technology tailored to the chromium(VI) challenge in households requiring effective treatment designed around usage demand and water chemistry.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2015-02-20. These figures describe the public water system's record, not the plumbing inside any individual building.
On record: EPA UCMR3 monitoring (2013-2015) for Wailuku (HI0000212), HI: 174 results across 2 listed contaminants, 174 detections above the reporting level; no federal MCL for hexavalent chromium; total chromium MCL 100 ug/L
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