Oxidation State Changes: From Surface Water to Your Tap
In Bexar County, surface water is the main supply for the San Antonio Water System, serving over 2.6 million people. Chromium in water exists in different chemical forms, with chromium-6 (hexavalent chromium, Cr(VI)) being more oxidized and chromium-3 (trivalent chromium) more reduced. The surface water source contains chromium-6 detected in the majority of samples at low levels measured in micrograms per liter (µg/L). As water travels from the source through treatment and distribution pipes to a household faucet, various chemical and biological processes can alter chromium's oxidation state. This means chromium-6 concentrations at the tap could differ from what is initially found in the source water or distribution system. Understanding these transformations is key to accurately assessing chromium-6 in your household water.
California’s 10 µg/L Chromium-6 Limit and Its Implications for Bexar County
California's public health policy established a 10 micrograms per liter limit for chromium-6 in drinking water due to concerns about potential health effects from long-term exposure. Although this limit is not federally mandated nor adopted in Texas, it provides context for evaluating chromium-6 levels detected in San Antonio’s water system. EPA’s unregulated contaminant data show the highest chromium-6 concentration in Bexar County’s system at 1.8 µg/L, well below California’s guideline. This state-level benchmark can help guide residential water quality considerations, but it does not determine safety or regulatory compliance in your area.
Natural Geogenic Sources Versus Industrial Contributions of Chromium-6
Chromium-6 in water may originate from natural sources such as the weathering of certain minerals in arid and alkaline aquifers common to parts of Texas. Industrial activities, including metal plating and manufacturing processes, can also release chromium-6 into the environment. In Bexar County’s surface water, monitoring reflects a mix of sources, though the detected levels do not indicate any compliance violations. Distinguishing geogenic (natural) chromium-6 from industrial inputs requires contextual environmental data and laboratory analyses to trace sources accurately.
Testing Priorities: From Basic Checks to Laboratory Analysis
If you are concerned about chromium-6 in your residential water, start with a water quality test for total chromium as some basic home testing kits may offer. However, only specialized certified laboratory testing can specifically quantify hexavalent chromium (chromium-6). These tests report chromium-6 in micrograms per liter or parts per billion (ppb), allowing comparison with area sampling data and reference limits. Because chromium speciation can vary from source to tap, testing your household water is essential for precise information rather than relying on system-wide or regional data.
How the C-Series Chromium-6 Filter Addresses Hexavalent Chromium
The C-Series Chromium-6 Filter, shipped ready to configure for home use, employs technology designed to reduce chromium-6 from household water. This treatment approach targets chromium(VI) specifically, helping to lower its concentration regardless of whether it originates naturally or from industrial sources. Using a documented filter model equipped for chromium-6 can provide a practical option to manage this constituent if test results show levels warranting attention based on your personal risk assessment or guideline preferences.
Deciding whether to test and address chromium-6 in your home water involves understanding the chemical changes it undergoes, referencing regional monitoring results like those from Bexar County’s San Antonio Water System, and knowing the available technologies. This page outlined how oxidation states differ in water phases, the significance of California’s threshold, source distinctions, testing steps, and a solution option for chromium(VI).
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