Pentair Chromium-6 Filter

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What the Oxidation State of Chromium Means from Source to Tap

Chromium can exist in different forms, notably chromium-3 and chromium-6 (also called hexavalent chromium or chromium(VI)). The form observed depends on chemical conditions and treatment processes. In Laramie’s public water system, chromium is sourced from surface water and undergoes treatment and distribution before reaching household taps. Oxidation states can shift during these stages, meaning chromium detected at the source may appear differently at the tap. Understanding these changes is important for interpreting water quality reports and deciding if further testing of your own water is needed.

Why California’s 10 µg/L Threshold for Chromium-6 Sheds Light on the Issue

California has established a public health goal for chromium-6 at 10 micrograms per liter (µg/L or parts per billion). This number reflects a precautionary approach based on toxicological studies and policy decisions unique to California. However, this threshold is not a federal legal limit and does not apply to Laramie’s water system. The EPA has not set a maximum contaminant level (MCL) for chromium-6 separately; the total chromium MCL remains at 100 µg/L. As such, readings below the total chromium MCL in Laramie should not be interpreted as health-based violations.

How Public Water System Records Differ from Private Well Testing

The data reported for the City of Laramie come from public water system monitoring under federal unregulated contaminant monitoring rules (UCMR3). These results represent water quality at the treatment plant or within the distribution system, averaged over many samples and connections. They offer an overview of chromium-6 occurrence affecting thousands of people but do not provide information about any individual household’s water. Testing a private well would require separate sampling because the chromium-6 concentration can vary significantly by location, source, and plumbing.

Reading the Record’s Median and Range as a Homeowner in Laramie

From 2013 to 2015, the City of Laramie’s water system recorded 26 measurements for chromium-6, with 21 showing detection above 0.03 µg/L. The highest result measured was 0.51 µg/L, while the median detected concentration was 0.31 µg/L. For total chromium, 16 detections were above 0.2 µg/L with a highest value of 1.2 µg/L and a median of 0.305 µg/L. All these values fall well below the federal total chromium MCL of 100 µg/L. These numbers are not safety violations but indicate that chromium-6 is present at low levels in the system.

What the UCMR3 Nationwide Survey Was Designed to Learn — and Its Household Limits

The EPA’s Unregulated Contaminant Monitoring Rule (UCMR3) survey aimed to gather occurrence data on contaminants like chromium-6 without establishing enforceable limits. Its purpose was to inform future regulatory decisions and assess the presence of emerging contaminants. For residents, these results provide context about water quality trends across the system but do not replace private water testing for specific household decisions. UCMR3 data are not intended to diagnose individual water supply issues.

Household Signs That May or May Not Relate to Chromium-6 in Water

Chromium-6 presence at the low levels recorded in Laramie’s system typically does not produce noticeable taste, odor, or staining effects. Symptoms such as unusual tastes or health concerns should prompt water quality testing to identify causes. However, the presence of chromium-6 alone at reported levels does not correlate with such symptoms. For those seeking targeted reduction of chromium-6 to address concerns or preferences, direct purchase of the Pentair Chromium-6 Filter ships ready to configure and is designed to reduce chromium(VI) in residential water.

Summary: What the Laramie Water Quality Record Establishes

The City of Laramie’s public water system record from EPA monitoring confirms chromium-6 occurs at low microgram-per-liter levels, well below federal maximum contaminant levels. This occurrence data serves as a broad indicator for the service area and is not a substitute for any single household’s water quality test. For detailed information, the EPA’s public water system record is the authoritative source.

Where this information comes from

Source: EPA SDWIS public water system record. Sampled 2013-11-19. These figures describe the public water system's record, not the plumbing inside any individual building.

On record: EPA UCMR3 monitoring (2013-2015) for City of Laramie (WY5600029), WY: 52 results across 2 listed contaminants, 37 detections above the reporting level; no federal MCL for hexavalent chromium; total chromium MCL 100 ug/L