Government data from the EPA’s UCMR3 monitoring shows that the Westerly Water Department, serving Washington County, Rhode Island, had chromium-6 detected in all 16 samples collected from 2013 to 2015, with concentrations ranging between 0.03 and 0.26 micrograms per liter (µg/L). No health-based violations were reported in this system’s record.
Scope and Limits of the UCMR3 Monitoring Survey
The UCMR3 Survey’s Goal
This nationwide survey aimed to measure unregulated contaminants like chromium-6 in public water systems to establish occurrence levels. It relied on sampling at system points, not individual homes, so it does not reveal specific household water quality.
Implications for Household Water Testing
Because UCMR3 data represents system-wide averages or ranges, only a private test of your home's water can show the exact chromium-6 concentration at your tap.
Chromium Oxidation State Changes from Source to Tap
Chromium Speciation in Groundwater
Chromium in groundwater can exist mainly as hexavalent chromium (chromium-6) or trivalent chromium (chromium-3). The chemical form can shift due to changes in water chemistry and oxygen levels as water moves through wells and distribution pipes.
Effect on Tap Water Quality
The oxidation state may decrease or increase slightly before reaching the tap, but such changes depend on local chemistry, which only direct testing can characterize.
How Treated Water Differs at the Tap with Chromium-6 Technology
Impact of Specialized Filtration
Using the Fleck Chromium-6 Filter technology that ships ready to configure can help address hexavalent chromium presence by acting on chromium-6 specifically, aiming for improved water quality at the tap distinct from the untreated distribution supply.
Technical Approach Overview
The Fleck system applies filtration methods designed to affect chromium-6 levels without affecting total water supply quality in undesirable ways.
Distinguishing Trivalent and Hexavalent Chromium
Total Chromium Data Does Not Specify Chromium-6
EPA data reports both chromium-6 and total chromium concentrations separately. Total chromium results do not differentiate between chromium’s oxidation states, so a total chromium reading cannot substitute for chromium-6 measurement.
Why This Matters
Hexavalent chromium and trivalent chromium have different chemical properties and potential effects, making the distinction critical in assessing water quality and treatment needs.
Public-System Records Versus Private-Well Testing
System Records Reflect Overall Water Source and Treatment
Public water system results provide a broad view of contaminants detected in the treated groundwater supply serving many customers, helpful for understanding regional water quality trends.
Limitations for Individual Household Assessment
They do not indicate the concentration at a particular home’s tap; household testing is essential to know exact chromium-6 levels in private wells or at the point of use.
Sources of Chromium-6 in Westerly’s Groundwater
Geological and Human Factors
Chromium-6 enters groundwater through natural erosion of rocks containing chromium compounds and potential industrial or urban activities in the region. The local geology influences baseline chromium levels in the groundwater supply.
System Water Source
Westerly’s public water system relies on groundwater, making understanding local geology and historical land use part of evaluating chromium-6 presence.
Choosing how to address chromium-6 in household water involves understanding system-wide occurrences from government data, recognizing that oxidation states can vary from source to tap, and considering technology that targets chromium-6 directly.
Testing your own water is the only way to determine specific chromium-6 levels at your tap and to decide if the Fleck Chromium-6 Filter is an appropriate technical approach for your household’s water treatment.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2015-09-16. These figures describe the public water system's record, not the plumbing inside any individual building.
On record: EPA UCMR3 monitoring (2013-2015) for Westerly Water Department (RI1559512), RI: 32 results across 2 listed contaminants, 19 detections above the reporting level; no federal MCL for hexavalent chromium; total chromium MCL 100 ug/L
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