Government Sampling Data on Chromium-6 in Bexar County
The San Antonio Water System, serving over 2.6 million people in Bexar County with surface water, was monitored for hexavalent chromium (chromium-6) under the EPA's UCMR3 survey from 2013 to 2015. Of 145 samples taken, chromium-6 was detected in 136, with the highest recorded concentration at 1.8 micrograms per liter (µg/L), or parts per billion (ppb), and the median of detections at 0.096 µg/L. Importantly, no health-based violations have been recorded for this water system under EPA standards.
1. Trivalent versus Hexavalent Chromium: Why Total Chromium Levels Don't Tell the Whole Story
Total chromium measurements include all forms of chromium present in the water, but they do not specify the amount of hexavalent chromium, or chromium(VI), which differs chemically and biologically from trivalent chromium, or chromium(III). While total chromium levels in Bexar County samples reached up to 6.3 µg/L, this figure doesn't isolate chromium-6 concentrations. Differentiating these two oxidation states is vital since chromium-6's behavior and treatment differ from chromium(III).
2. California's Chromium-6 Limit and Its Significance for Bexar County Residents
California has established a Public Health Goal of 10 µg/L for chromium-6, a level derived from studies assessing potential health risks. Although Bexar County's municipal water system has chromium-6 concentrations well below this threshold, the standard reflects a cautious approach to this constituent. Residents outside California can view this limit as an informative reference, though local regulatory and health assessments do not designate these chromium-6 levels as violations or unsafe.
3. Scope of Sampling: What the Number of Samples and Sources Means
The data from 145 samples cover a broad spectrum of points within the San Antonio Water System's service area, representing 881,243 connections. This extensive monitoring provides a regional snapshot rather than a direct measure of any individual home's water. Consequently, local variations in chromium-6 concentration can occur, underscoring the importance of specific testing at the point of use when questions arise.
4. Changes in Chromium Oxidation State from Source to Tap
The oxidation state of chromium can shift between the water source, treatment facilities, distribution systems, and household taps. Factors such as water chemistry and disinfectant use may influence chromium speciation, potentially altering the balance between chromium(III) and chromium(VI) by the time water reaches consumers. Thus, chromium-6 levels measured at centralized points may differ from those at individual taps.
5. Steps to Identify Chromium-6 Conditions in Your Home Water
When existing water treatment equipment has failed, begin by checking visual signs such as staining or taste changes. Next, examine local water quality reports for your system. For precise evaluation, the key step is to obtain a laboratory water test that quantifies chromium-6 specifically. This test is the most direct way to understand your household water's chromium-6 concentration and to determine the treatment needs moving forward.
6. How the Pentek Chromium-6 Filter Helps Manage Hexavalent Chromium Concerns
The Pentek Chromium-6 Filter ships ready to configure for home water lines and uses documented filtration technology designed to reduce chromium(VI) levels. Though it is not a cure-all, this equipment addresses chromium-6 by effectively adsorbing or neutralizing the constituent, helping restore water quality where previous treatment has failed.
Next Step: Ordering a Targeted Chromium-6 Water Test
To clarify your home's water status conclusively, order a laboratory analysis that measures hexavalent chromium concentration. A result significantly below the California health-related guideline would reassure you of minimal chromium-6 presence, while a higher result signals the need for continued filtration or alternative treatment options. This test provides the evidence base for making informed decisions about water quality management after treatment equipment failure.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2015-12-04. These figures describe the public water system's record, not the plumbing inside any individual building.
On record: EPA UCMR3 monitoring (2013-2015) for San Antonio Water System (TX0150018), TX: 290 results across 2 listed contaminants, 229 detections above the reporting level; no federal MCL for hexavalent chromium; total chromium MCL 100 ug/L
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