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Shortlist

Contaminant

Chromium-6 in drinking water

Also listed as Chromium-6 · Chromium 6 · Cr-6 · Chromium (VI)

The “Erin Brockovich” chemical: a carcinogen from industrial pollution.

This page can’t tell you what’s in your tap water.
Only a test of water from your own tap can. Public-system results describe the system, not your home.
6 sources
01Check your water systemWater Check · system results, not your tap02Test your tapHow to get a reliable result03Treatment approachesWhat can reduce it at the tap
On this page · 10 sections
  1. 01Reference values
  2. 02Is it in my water?
  3. 03Where it comes from
  4. 04Testing
  5. 05Water filters
  6. 06Treatment
  7. 07Evidence
  8. 08Next steps
  9. 09Ask about chromium-6
  10. 10References
Reference values

No federal limit for Chromium-6 — one state sets its own.

Each value says what kind of reference it is, and they mean different things. A lower or missing number never means water is safe.

State limit · MCLCalifornia state limit
10 ppb

An enforceable limit for public water systems in that state.

Applies to
Public water systems in that state, not private wells
Status
In force
Source
California state MCL (hexavalent chromium, 10 µg/L) · 22 CCR §64431 (Table 64431-A)
Is it in my water?

Only a test of your own tap can tell.

Choose what you have. We’ll show what it can and can’t tell you.

If you haven’t tested
Nobody can tell without a measurement, including us.

Three things you can do, in this order.

Test water from your tapThis is the only way to know your level. Testing guidance ↓See what your system reportsSystem results aren’t a tap measurement. Open Water Check →On a private well?Public-system reports don’t cover wells. Open Well Water →
Where it comes from

Where it comes from

  1. Naturally occurring chromium in igneous geologic formations
  2. Industrial processes including steel making, metal plating, leather tanning, and wood preservatives
  3. Oxidation of naturally occurring chromium during water disinfection
  4. Industrial leakage, poor storage, or improper disposal practices
Why it matters
Hexavalent chromium is a known human carcinogen and a major drinking water concern; the EPA has taken regulatory action to address it and the World Health Organization maintains a guideline for total chromium at 0.05 mg/L
Testing

How to test your tap water for chromium-6

Hexavalent chromium can be monitored through sampling and analysis; water systems serving more than 10,000 people are required to monitor for both total chromium and hexavalent chromium under EPA Unregulated Contaminant Monitoring Rule 3.

  1. 01Use a certified labA state-certified lab, or a kit that sends samples to one.
  2. 02Follow the sampling stepsHow and when you collect the water changes the result.
  3. 03Check the reportIt should state units and the detection limit.
Certified labNot sponsored
Use a state-certified labYour state keeps a list of labs certified for drinking water.

Choosing a filter for chromium-6

None qualify
No products currently qualify for a chromium-6 pick here.

Nothing in our database has a chromium-6 claim for an exact configuration we can verify.

Find a fit in FinderRead treatment approaches
Treatment

How to reduce chromium-6 in water

Function: ReduceAnion exchange removes hexavalent chromium by exchanging negatively charged chromium ions with more benign ions on a synthetic resin; adsorptive media such as aluminum-based or iron-based materials can also remove chromium by adsorption to the media surface depending on water chemistry conditions like pH.
How to reduce chromium-6Reverse osmosis is the most reliable certified route (NSF/ANSI 58), and some specialized reduction or anion media also capture it. Confirm the claim names chromium-6 or total chromium, not just “heavy metals”.
Whole-house systems and point-of-use filters treat different water. A whole-house system treats water where it enters the home; a point-of-use filter treats the tap it’s installed on. Check which one a claim is for.
Evidence

What the evidence means

We keep evidence types apart. A result for one configuration never stands in for another, and we never average across types.

No product in our database holds a reduction record for chromium-6 yet.

How we read evidence →

Next steps

Take the next step

Match a system to your homeFinder asks about your home first. It suggests chromium-6 as a starting point, and nothing counts until you confirm it.
Ask about chromium-6

Still have a question?

Answers come only from WaterDecoder’s reviewed sources and show citations. Ask can’t interpret your test result or choose a product. Don’t include personal details.

AI assistant

Ask about Chromium-6

Answers draw on cited public-health sources and the filters certified to reduce Chromium-6. Every source is linked, and if the sources don’t cover a question, the answer says so.

Questions to start with

Educational information from cited sources. Not medical or professional advice.

References

Where these facts come from

  1. 1Regulatory reference22 CCR §64431 (Table 64431-A)California state MCL (hexavalent chromium, 10 µg/L)
  2. 2Knowledge BaseOverview of Drinking Water Treatment TechnologiesUS EPA (SDWA program)
  3. 3Knowledge BaseChromium in Drinking Water: A Technical Information PrimerAmerican Water Works Association (AWWA)
  4. 4Knowledge BaseHexavalent Chromium (Chromium-6)California State Water Resources Control Board (SWRCB)
  5. 5Knowledge BaseChromium in Drinking WaterUS EPA (Safe Drinking Water Act program)
  6. 6Knowledge BaseChromium Hexavalent Compounds - Report on Carcinogens, 15th EditionNational Toxicology Program (NIH/HHS)

Written and maintained by WaterDecoder. A review date appears only once we have confirmed one.

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