If You See Chromium-6 Detected in Area Public Water System Reports, What Does It Mean for Your Home?
It's common to find chromium-6, also called hexavalent chromium or Cr(VI), listed in public water system monitoring records. But these detections are federal measurements from surveys, not safety alerts specific to your tap. The EPA's unregulated contaminant monitoring rule (UCMR3) conducted testing between 2013 and 2015, compiling data to better understand occurrence patterns, not to set enforceable limits.
For the Water & Power Authority (St. Thomas) system in VI, chromium-6 was detected in half of the eight samples analyzed, with measurements ranging up to 1.0 micrograms per liter (µg/L), or parts per billion (ppb). These results are well below the total chromium maximum contaminant level of 100 µg/L. The data identifies presence but cannot determine your household's water condition without your own testing.
If You Wonder How Chromium-6 Changes From Source to Your Tap
Hexavalent chromium exists in water as chromium(VI), an oxidation state of chromium known for higher mobility and solubility compared to other forms. However, chemical reactions can alter its form between the groundwater source, distribution pipes, and the faucet.
Factors like pH, presence of reducing agents, and pipe material can transform chromium(VI) to trivalent chromium (Cr(III)), which is less soluble and reactive. This means that chromium-6 detected at a source may partially or fully convert by the time it reaches your home, complicating assumptions based solely on system-wide sampling.
If You Consider the Number of Samples Behind the Monitoring Data
The EPA's UCMR3 data for this system is based on eight chromium-6 samples collected over several months. While useful for understanding general occurrence, only a small number of tests limits precise conclusions about variability across the entire supply area or time.
Random fluctuations, localized chemistry, and sampling points can impact results. Therefore, the presence of chromium-6 detections in these limited tests does not predict the level in any one household's water, which could be higher or lower.
If You Are a Commercial or Industrial User, You Face Additional Considerations
While homeowners typically focus on health and appearance, commercial and industrial water users also evaluate metal concentrations for equipment longevity, regulatory compliance, product quality, and process needs.
They may conduct more detailed, ongoing monitoring, including at multiple locations and depths, as well as consider water treatment technologies matched to specific operational requirements. Residential users have fewer such complexities but may still benefit from targeted solutions if their water tests show chromium-6 presence.
If You Rely on Public Water System Records Versus Private Well Testing
Data from public water systems like the Water & Power Authority (St. Thomas) documents occurrence at the system level. This reflects water quality at entry points to distribution but not necessarily at individual homes.
Private wells require direct sampling to establish their unique water chemistry, as they can differ significantly from public supplies due to local geology and hydrology. Public system records provide context but cannot substitute for individualized water testing if you have your own well or want precise household data.
If You Wonder How Chromium-6 Enters Groundwater and Public Water in VI
Chromium-6 in groundwater generally originates from natural geological formations releasing chromium compounds into aquifers or from historical industrial activities affecting regional water sources. In VI, monitoring indicates low-level presence consistent with natural occurrence and trace anthropogenic inputs.
This chromium(VI) can dissolve and move through aquifers feeding public system wells. Its concentration depends on local geochemistry, water flow, and redox conditions. Understanding these factors helps evaluate potential for chromium-6 occurrence and informs water quality management.
Summary: The public water system record for the Water & Power Authority (St. Thomas) in VI shows chromium-6 was detected at low levels in federal UCMR3 monitoring but without any health-based violations. This data reflects system-wide conditions, not specific household water. To know your water’s chromium-6 level, testing your tap water is necessary. The C-Series Chromium-6 Filter ships ready to configure and provides a documented solution to address chromium(VI) concerns at the point of use when needed. For detailed data, see the EPA's official monitoring results for system VI0000443.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2014-11-05. These figures describe the public water system's record, not the plumbing inside any individual building.
On record: EPA UCMR3 monitoring (2013-2015) for Water & Power Auth. (St. Thomas) (VI0000443), VI: 16 results across 2 listed contaminants, 8 detections above the reporting level; no federal MCL for hexavalent chromium; total chromium MCL 100 ug/L