Chromium-6 in Tap Water
Hexavalent chromium (chromium-6) is a form of chromium from industrial processes and some natural deposits, the contaminant made famous by the Erin Brockovich case.
Industrial discharge (metal plating, manufacturing) and some natural geological sources.
- 1Industrial / metal-plating discharge
- 2Natural geological deposits
Most affected: The general population served by an affected system; long-term exposure is the concern.
A result is read with its context
Where reported, from occurrence monitoring; not every system reports chromium-6 separately from total chromium. PurityMap does not yet publish a per-system measured value for Chromium-6; this page is a reference explainer. To learn what is in your own water, check your utility’s Consumer Confidence Report (CCR) or use a certified home test.
- Above reference
- Evidence exceeds a reference level.
- Detected
- This substance was found in the monitoring record. Being present is not the same as being above a reference level, and this signal does not say which.
- Not detected
- Somebody looked and the laboratory reported nothing above its reporting limit. This is a result, and it is not the same as nobody looking.
- Not monitored
- No sampling for this substance has been reported for this system. Nothing is known either way, and an empty row is not a clean one.
No city results or violations published yet
- MeasurementsPendingNo per-system values
PurityMap does not yet publish a measured value for chromium-6.
- ViolationsCheckedNone on the federal record
No city in PurityMap’s record has a chromium-6 violation in EPA SDWIS since 2016.
- CitiesPendingNo detections on record
No city in PurityMap’s record shows chromium-6 detected.
This fills in as monitoring data is published. Until then, your utility’s Consumer Confidence Report lists its results, or use a certified home test.
What can carry a chromium-6 reduction claim
- Reverse osmosis
Semi-permeable membrane separation removing dissolved minerals, heavy metals, and persistent fluorinated chemicals down to 0.0001 microns.
- Anion exchange
Synthetic polyvalent resin beads that exchange unwanted dissolved ionic contaminants for harmless benchmark ions.
- Reduction / filtration systems
Boiling does not remove a dissolved chemical compound and can concentrate it. Many pitcher and refrigerator filters carry no verified claim for a compound like this at all.
A finding establishes the need, the need names the capability, the capability requires a verified certification. No product appears before that sequence completes. Filter Finder →
Frequently asked
Answers cite the same records as the page. How PurityMap analyzes water data
Hexavalent chromium (chromium-6) is a form of chromium from industrial processes and some natural deposits, the contaminant made famous by the Erin Brockovich case.
There is no enforceable federal limit. The record reads: No dedicated federal Cr-6 limit; total chromium 100 µg/L. California sets a Cr-6 MCL of 10 µg/L.. PurityMap reads every measurement against its stated benchmark and never sets its own.
Industrial / metal-plating discharge, Natural geological deposits.
Chromium-6 is a known carcinogen when inhaled and is associated in studies with cancer risk from ingestion. Federal rules regulate total chromium; some states (notably California) set a stricter chromium-6 limit.
Treatment technologies commonly certified to reduce Chromium-6 include Reverse osmosis, Anion exchange, Reduction / filtration systems. Match the exact certified claim to your water before buying. Holding a format is not the same as holding the claim.