Understanding Chromium Speciation from Source to Tap
Chromium in water appears primarily in two oxidation states: trivalent chromium (Cr(III)) and hexavalent chromium (Cr(VI)), also known as chromium-6. The form entering the household may differ from that in the groundwater due to chemical reactions during water treatment and distribution. Groundwater is typically more reducing, favoring chromium(III), but water treatment processes and exposure to oxygen in the distribution system can oxidize chromium to hexavalent chromium by the time water reaches the tap. This change impacts which treatment methods will be effective inside the home.
Sources of Hexavalent Chromium in Hartford County's Water Supply
The public water system serving Avon, Farmington, and Simsbury in Hartford County draws from groundwater. Chromium-6 detected in these supplies is generally understood to have a geogenic origin, naturally occurring in the local aquifer geology characterized by specific mineral deposits. This contrasts with chromium-6 from industrial sources, such as metal plating or manufacturing, which tends to occur near industrial facilities and can exhibit different chemical behaviors.
How Advanced Filtration Technology Addresses Hexavalent Chromium
The Pentek Chromium-6 Filter uses a specialized medium designed to reduce chromium(VI) levels in residential water by converting or capturing the chromium-6 species effectively. It ships ready to configure for household water lines and is documented to handle concentrations in the range found in Hartford County's system records. This filtration technology targets the hexavalent chromium form, which is of primary concern due to its higher mobility and chemical characteristics compared to chromium(III).
Pathways of Hexavalent Chromium into the Local Groundwater and Distribution System
Chromium-6 enters groundwater in this region through natural geological processes, slowly leaching from mineral formations in the aquifer. The Avon Water Co., serving over 11,500 residents via groundwater sources, has recorded chromium-6 detections consistently between 0.03 and 1.0 micrograms per liter (ppb), though no health-based violations have been recorded. The distribution system’s exposure to oxygen and treatment chemicals may influence the chromium speciation at the tap.
Household Fixtures and Uses Most Impacted by Chromium-6 Presence
Fixtures with frequent water contact, such as kitchen faucets, drinking water outlets, and bathroom taps, are typically the first points where any issues related to chromium-6 occur. Appliances like coffee makers or ice machines that rely on tap water filtration or heating may also be affected. These points reflect immediate water quality and are where effective chromium-6 filtration provides the greatest benefit.
Seasonal and Multi-Year Fluctuations in Chromium-6 Concentrations
The UCMR3 monitoring from July 2013 to February 2014 shows chromium-6 detections in all tested samples from the Avon Water system, with the highest reading at 1.0 micrograms per liter and a median of 0.405 micrograms per liter. These results demonstrate stability over this monitoring period without significant seasonal variation, indicating a consistent presence of chromium-6 in the groundwater source.
Recommended Water Testing to Confirm Household Chromium-6 Levels
For homeowners concerned about chromium-6 and whether their current equipment remains adequate, the essential next step is direct testing of water at the tap. Testing should measure chromium-6 concentration specifically to determine if levels are stable or increasing beyond what the household equipment can handle. A confirmed chromium-6 concentration, compared against a documented range for the Avon Water Co., will clarify whether augmenting filtration with a Pentek Chromium-6 Filter is warranted.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2014-02-12. These figures describe the public water system's record, not the plumbing inside any individual building.
On record: EPA UCMR3 monitoring (2013-2015) for Avon Water Co. (CT0040011), CT: 64 results across 2 listed contaminants, 63 detections above the reporting level; no federal MCL for hexavalent chromium; total chromium MCL 100 ug/L
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