Oxidation State Changes Between Source, Distribution, and Tap
Hexavalent chromium (Cr(VI)), commonly known as chromium-6, is a form of chromium that can exist in differing oxidation states throughout water's journey from the source to your tap. In the Salt Lake City Water System, the chromium comes primarily from surface water sources. Chemical reactions involving oxygen and other elements during water treatment and distribution can alter chromium to various oxidation states. While chromium-6 is more soluble and mobile, it may transform partially into trivalent chromium (chromium-3), which behaves differently in water and in the body. However, the specific balance of chromium oxidation states at your tap depends on your household plumbing and water age, which government data does not measure directly.
The Nature of Hexavalent Chromium Sources in Arid, Alkaline Aquifers Versus Industrial Origins
Hexavalent chromium in water can originate from natural sources or industrial activities. In Salt Lake County, the geology includes arid and alkaline aquifers where small quantities of geogenic chromium-6 may be present due to natural rock weathering. Surface water supplies like those feeding the Salt Lake City Water System also can carry chrome traces from the environment. This contrasts with chromium-6 concentrations near industrial plating or manufacturing sites, which are not part of this public water system’s source. Understanding the difference helps to contextualize detections measured by federal monitoring.
Implications of Leaving Chromium-6 Untreated Over Years
Long-term presence of chromium-6 at low microgram-per-litre levels, as reported in Salt Lake City's public water data, does not constitute a violation or health-based exceedance. Nevertheless, households with existing filtration equipment might find that their systems are less effective over time as chromium-6 can pass through common filters or require specialized technology to address. Untreated chromium-6 does not cause immediate water quality failure like visible discoloration or taste alterations, but it may influence taste or staining at certain thresholds and typically requires dedicated filter media or targeted treatment methods for stable control.
The Purpose and Limits of the UCMR3 Nationwide Chromium-6 Monitoring Survey
The third Unregulated Contaminant Monitoring Rule (UCMR3) survey conducted between 2013 and 2015 gathered data on chromium-6 levels for public water systems, including Salt Lake City’s. The survey aimed to understand the occurrence of hexavalent chromium nationwide rather than compliance or individual household risk. For Salt Lake City Water System, 35 out of 37 samples detected chromium-6 above a reporting level of 0.03 micrograms per litre, with a highest recorded concentration of 2.0 micrograms per litre and a median at 0.35 micrograms per litre. These results serve as an informative snapshot of system-wide levels but do not provide a precise reading of chromium-6 at any single home’s tap.
Interpreting Certified Laboratory Tests for Chromium-6
If you decide to assess chromium-6 in your household water, a certified laboratory test is necessary. Such tests quantify chromium-6 in micrograms per litre (µg/L), equivalent to parts per billion (ppb). When reviewing your report, note the detection limits and compare results against local public water measurements. A certified test reflects conditions specific to your plumbing and water use, which government data cannot substitute. Understanding your individual results can guide decisions on supplemental water treatment and whether specialized filtration like the C-Series Chromium-6 Filter may be appropriate to supplement existing equipment.
What Area Data Should Not Lead You to Conclude
While federal data confirms chromium-6 is present in Salt Lake City’s water system at low microgram-per-litre levels, it does not establish any home's water as exceeding safety standards or requiring immediate corrective action. Detection is not equal to a violation or a health hazard. The total chromium at this system remains well below the 100 micrograms per litre federal maximum contaminant level (MCL). Before adjusting your water treatment strategy, testing your own water is essential. The C-Series Chromium-6 Filter ships ready to configure for supplemental control if your household equipment struggles to manage chromium-6 concentrations adequately.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2014-01-06. These figures describe the public water system's record, not the plumbing inside any individual building.
On record: EPA UCMR3 monitoring (2013-2015) for Salt Lake City Water System (UTAH18026), UT: 74 results across 2 listed contaminants, 65 detections above the reporting level; no federal MCL for hexavalent chromium; total chromium MCL 100 ug/L