What Local EPA Data Can and Cannot Tell You About Chromium-6
When considering chromium-6 in your household water in Washington County, MN, it is important to understand the limits of public water system data. The EPA’s unregulated contaminant monitoring results for the Oakdale water system—which serves over 30,000 people via groundwater sources—show multiple detections of chromium-6 (Cr(VI)) and total chromium. However, these figures represent the system's water quality overall, not a specific home’s water.
Though chromium-6 was detected in 9 out of 14 samples, with a maximum concentration of 0.74 micrograms per litre (µg/L, equivalent to parts per billion), no federal enforceable maximum contaminant level exists for chromium-6. Total chromium was detected up to 1.3 µg/L, well below the total chromium MCL of 100 µg/L. The EPA record for Oakdale shows no health-based violations related to chromium-6 or total chromium. To know the exact concentration in your own water, testing of your specific supply is necessary.
How Chromium Oxidation States Change from Well to Tap
Chromium exists primarily in two oxidation states relevant to drinking water: hexavalent chromium (chromium-6) and trivalent chromium (chromium-3). Chromium-6 is more soluble and mobile in groundwater, often detected at the wellhead. However, as water moves through distribution pipes and household plumbing, chemical conditions such as pH, oxidation-reduction potential, and organic matter can influence chromium’s transformation. This can convert chromium-6 to chromium-3, a less soluble and less mobile form. Thus, the chromium form at the tap may differ from that measured at the well or in the distribution system samples.
Implications of California’s 10 µg/L Chromium-6 Guideline for Washington County Residents
California has established a public health goal of 10 µg/L for chromium-6 in drinking water due to concerns over potential long-term health effects identified by state risk assessments. Washington County's water system concentrations are below this level, based on available monitoring data. While this guideline is not a federal regulatory limit, it provides context for understanding chromium-6 levels. Residents may consider this benchmark when evaluating the significance of any chromium-6 detected in their own water, especially if results approach or exceed that threshold.
How Water Appears at Your Tap After Using the Pentair Chromium-6 Filter
Once water passes through the Pentair Chromium-6 Filter, the chromium-6 content at the tap can be effectively reduced to help address aesthetic and chemical concerns. The filter uses specialized media designed to target and interact with hexavalent chromium ions. This process converts or removes chromium-6, resulting in water with lower chromium-6 levels delivered to your household taps. The finished water quality after treatment will depend on your home's water chemistry and the specific chromium-6 concentration present in your water source.
Mechanisms by Which the Pentair Technology Neutralizes Chromium-6
The Pentair technology incorporates advanced filtration media that adsorbs hexavalent chromium from the water stream. This media may facilitate redox reactions, changing chromium-6 to the less soluble and less mobile chromium-3 form within the filter matrix. The process significantly reduces chromium-6 concentration in the treated water, meaning that water leaving the filter to household taps contains much lower levels of chromium-6 than untreated water. The filter ships ready to configure for residential use.
Why Total Chromium Results Do Not Fully Reflect Chromium-6 Concerns
Monitoring results often report both total chromium and chromium-6 separately because total chromium measurements do not differentiate between chromium-3 and chromium-6. Chromium-3 is an essential nutrient at trace levels and is less of concern in terms of toxicity, whereas chromium-6 can have different chemical behaviors and considerations. Since total chromium includes both oxidation states, it cannot alone answer questions about chromium-6 exposure. For precise understanding, measurements specifically of hexavalent chromium are necessary.
Conclusion: Understanding Your Water Quality and Next Steps
The public water system record for Oakdale in Washington County provides a snapshot of chromium-6 presence in the groundwater-derived supply, showing low-level detections below health-based violations. This data does not represent individual homes but serves as a regional reference point. For household-specific knowledge, water testing for chromium-6 is recommended. The Pentair Chromium-6 Filter offers a documented technology to reduce chromium-6 at the tap effectively. For more detailed data, consult the EPA's public water system occurrence dataset.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2015-07-14. These figures describe the public water system's record, not the plumbing inside any individual building.
On record: EPA UCMR3 monitoring (2013-2015) for Oakdale (MN1820016), MN: 28 results across 2 listed contaminants, 19 detections above the reporting level; no federal MCL for hexavalent chromium; total chromium MCL 100 ug/L