Laboratory Test Report Elements for Chromium-6 in Source Water
Chromium-6 Concentrations Are Measured in Micrograms per Liter or Parts per Billion
Laboratory reports indicate chromium-6 (Cr(VI)) levels as numeric values representing micrograms per litre (µg/L), equal to parts per billion (ppb). For Camden District in Kent County, EPA UCMR3 data from 2013-2015 showed 20 sampling points with 4 detecting chromium-6 above the reporting level of 0.03 µg/L, with a maximum measured value of 0.93 µg/L and a median detected concentration of 0.505 µg/L. These figures apply to the system’s groundwater source and not individual residences.
Oxidation State Changes from Groundwater through the Distribution System to the Tap
Chromium Chemistry Can Shift Between Hexavalent and Trivalent Forms
Chromium-6, or hexavalent chromium, can undergo chemical changes as water moves from the well through pipes to the consumer tap, occasionally converting to trivalent chromium (chromium-3). Oxidation state changes depend on local water chemistry, such as pH, oxidation-reduction potential, and organic content. Because of this, a chromium-6 concentration detected in the groundwater is not necessarily identical at the tap.
Total Chromium Does Not Distinguish Chromium-6 from Other Forms
Total chromium measurements include both chromium(III) and chromium(VI). Camden District reported total chromium detections up to 0.9 µg/L, with no federal Maximum Contaminant Level (MCL) set for hexavalent chromium, while total chromium has an MCL of 100 µg/L. These values show chromium is present but cannot specify chromium-6 levels alone.
Purpose and Limits of the UCMR3 Nationwide Survey
The Survey Provides System-Wide Occurrence Data, Not Individual Household Results
The EPA’s Unregulated Contaminant Monitoring Rule 3 (UCMR3) was designed to gather occurrence information for various contaminants including chromium-6 across public water systems. Data from 2013 to 2015 represent system-wide groundwater monitoring for Camden District and cannot be used to determine an individual home’s chromium-6 content or exposure.
Detection Does Not Indicate a Violation or Health Risk
Chromium-6 detections serve to inform researchers and regulators about presence levels but do not constitute violations or imply water is unsafe. Camden District has no EPA health-based violations on record related to chromium or chromium-6.
Treatment Approaches: Ion Exchange versus Reverse Osmosis for Hexavalent Chromium
Ion Exchange Specifically Targets Chromium(VI) Ions
Ion exchange methods use resins that attract and hold chromium-6 ions from water, effectively reducing their concentration. This method is selective for chromium(VI) and usually preserves water flow rates better than some filtration types.
Reverse Osmosis Filters Remove a Broader Range of Contaminants
Reverse osmosis membranes filter out many dissolved substances including chromium-6, total chromium, and other dissolved solids by pushing water through a semi-permeable membrane. This process may involve more water waste and maintenance but provides more comprehensive filtration beyond chromium-6.
Distinguishing Between Trivalent and Hexavalent Chromium
Testing for Total Chromium Cannot Identify Chromium-6 Specifically
Chromium analyses that report only total chromium do not provide information on the proportion of chromium present as chromium-6 versus chromium-3. Since chromium-6 and chromium-3 have different chemical behaviors and health considerations, testing specifically for chromium-6 is necessary to assess this constituent.
Household Fixtures and Processes Most Sensitive to Chromium-6 Presence
First Points of Water Use May Show Chromium-6 Effects
Fixtures such as kitchen taps, ice makers, and appliances using water filtration can be the first locations where chromium-6 presence matters, especially if this constituent affects taste or requires targeted treatment. Treatment devices configured for chromium-6 should be placed accordingly.
What the Camden-Wyoming Area Data Do Not Reveal
Area Sampling Does Not Determine Your Home’s Chromium-6 Level
Although government data indicate the presence of chromium-6 in the Camden District system, individual water quality varies by property, well, and plumbing materials. Personal water testing for chromium-6 is necessary to define household conditions.
Detected Levels Are Not Safety Violations or Warnings
The detections in this area remain well below federal MCLs for total chromium, and there is no established MCL for chromium-6 itself. The absence of health-based violations on record means that the water system complies with EPA standards relevant to chromium.
Choosing Treatment Depends on Your Specific Water Testing
Determining which treatment solution fits your household requires testing your water’s chromium-6 concentration. The Pentek Chromium-6 Filter ships ready to configure and employs technology tailored to address this constituent effectively when needed.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2015-07-22. These figures describe the public water system's record, not the plumbing inside any individual building.
On record: EPA UCMR3 monitoring (2013-2015) for Camden District (DE0000124), DE: 40 results across 2 listed contaminants, 6 detections above the reporting level; no federal MCL for hexavalent chromium; total chromium MCL 100 ug/L