The difference between trivalent and hexavalent chromium, and why California tracks Chromium-6 separately when federal rules currently don’t.
Data current as of July 2026
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Chromium occurs in drinking water in two different forms, and the distinction matters a lot for what it means for your health.
Chromium (Total)
Occurs in two forms — trivalent (an essential nutrient in trace amounts) and hexavalent (linked to increased cancer risk).
Chromium-6 (Hexavalent)
The specific form of chromium linked to increased cancer risk at elevated exposure. California tracks it separately; federal rules currently do not.
Why California tracks it separately
Federal drinking water rules currently regulate "total chromium" as a single combined measurement, without distinguishing between the relatively harmless trivalent form and hexavalent chromium specifically. California's state water board tracks hexavalent chromium as its own separate analyte, which is why you'll sometimes see it broken out on a California-specific water quality report even when the federal violation record only shows total chromium.
Filtration
Chromium falls in the Metals category — reverse osmosis is generally the most broadly effective single technology against metals, though not every RO system is certified for every substance. Check for NSF/ANSI 53 or 58 certification for chromium specifically if it's a concern for your area.
Live in this area? Simple Water Heater & Filtration can size a filtration system to whatever's actually on file for your utility.