Chromium-6 · in your tap water
Industrial / pipe corrosion · cancer
Hexavalent chromium (the form famously documented in Erin Brockovich) enters water mainly from industrial discharges (electroplating, leather tanning, chromate manufacturing) and from naturally occurring geologic deposits. The EPA regulates 'total chromium' at 100 ppb but has no separate federal limit for the hexavalent form; California adopted its own chromium-6 limit of 10 ppb (effective October 2024), and the health-protective benchmark — California's public-health goal, which EWG also uses — is 0.02 ppb. IARC classifies chromium-6 as a Group 1 human carcinogen.
This is the Erin Brockovich one. RO is the only filtration approach that reliably handles it.
There is no separate federal limit for chromium-6 — the EPA regulates total chromium at 100 ppb and is still developing its hexavalent-chromium assessment. California set its own chromium-6 limit of 10 ppb (effective October 2024); the health-protective benchmark is California's 0.02 ppb public-health goal, which EWG uses.
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Every source below was checked to make sure the link works and backs the claim it's next to. These are the primary regulators and peer-reviewed studies — not our opinion.
Total-chromium MCL of 100 ppb; no separate federal hexavalent limit; IRIS review ongoing.
California's chromium-6 MCL of 10 ppb (effective Oct 2024) and the 0.02 ppb public-health goal.
Documents the 10 ppb adoption (2024) and the 2014 standard's 2017 court repeal.
Chromium(VI) is a Group 1 human carcinogen (lung cancer by inhalation).
'Clear evidence of carcinogenic activity' from chromium-6 in drinking water (rodent oral study).
Background on Erin Brockovich / Hinkley, CA and the chromium-6 cancer evidence.
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Get my free water report Book a free checkupThis page is general water-quality education, not medical advice. Health classifications and limits are attributed to the EPA, EWG, IARC, ATSDR/CDC, WHO and the cited studies. Contaminant levels vary by water system and home — the only way to know what's in your water is to test it. Prepared by SwiftPro Heating, Cooling & Plumbing.