Chromium (Total)
One number covering two very different chemicals — one a nutrient, the other a carcinogen.
- Safe range
- 0 – 0.1 mg/L (US EPA primary standard for TOTAL chromium, set conservatively because it cannot distinguish the nutrient form from the carcinogenic one. Some states set a separate, tighter limit on chromium-6.)
- Measured in
- mg/L
What it is
Chromium occurs naturally in rocks and soil and is used heavily in industry. The enforceable limit is on TOTAL chromium, which lumps together chromium-3, a trace nutrient the body needs, and chromium-6, an established carcinogen.
Why it matters
That lumping is the thing to understand about this reading. A total chromium result cannot tell you which form is present, and the two differ enormously in what they mean for health. EPA regulates the total on the conservative assumption that it could all be chromium-6; some states have moved to regulate chromium-6 separately, and California's efforts on it are the best known. So a total figure well under the limit is reassuring, and a figure approaching it is a reason to ask for speciation rather than to panic.
How to measure it
A laboratory panel gives you total chromium. If that comes back meaningful, a second, different test gives you the part that matters.
Certified laboratory, mail-in kit
- How trustworthy
- Reference grade
- Cost
- Most expensive
- Effort
- Careful sampling, then days or weeks of waiting
You are posted bottles and instructions, you fill them exactly as told, and you post them back. Weeks later a report arrives with figures nobody has to interpret by eye. This is what a result you intend to act on should be built from.
Total chromium is in most metals panels. Chromium-6 is a separate line item, usually costs more, and has to be asked for.
Watch out: Chromium-6 samples often have a short holding time and sometimes need field preservation. Order the correct kit rather than sending an ordinary bottle, or the result comes back low for the wrong reason.
Where to find it: State-certified drinking water laboratories; your state's certification officer keeps the list, and many public health departments will point you at one.
Your utility's annual water quality report
- How trustworthy
- Reference grade
- Cost
- Free
- Effort
- A few minutes of reading
Every community water system in the US has to publish one each year, free, listing what it found and what the limits are. It is real laboratory data about the water leaving the plant and travelling the mains. What it cannot describe is your own plumbing.
Public systems publish total chromium. Some also report chromium-6 voluntarily or under state rules.
Where to find it: Your water bill, your supplier's website, or the EPA's index of reports. It is also called a Consumer Confidence Report or CCR.
Further reading: US EPA: National Primary Drinking Water Regulations, the enforceable health-based limits; US EPA: certified drinking water laboratories, by state
If it is too low
Nothing to act on.
- • No action needed.
If it is too high
Worth speciating before deciding anything. If the bulk of it is chromium-6, the health concern is materially greater than the total figure alone suggests.
- • Order a chromium-6 test specifically. It is a different analysis and it is the one that decides how much this matters.
- • Reverse osmosis removes both forms at the tap; anion exchange targets chromium-6 for a whole house.
- • Check whether there is industrial plating, tanning or metal finishing upstream of your well.
Common questions
Is this the chromium from the Erin Brockovich case?
That case was about chromium-6 specifically, which is one component of this reading. A total chromium result includes it but cannot separate it out, so it neither confirms nor rules out the thing people mean when they ask.
Is any chromium in water good for me?
Chromium-3 is a trace nutrient, and it is obtained from food rather than needing to come from water. There is no benefit to having it in your supply, so a low result is simply a good result.
WiseWaterGauge helps you record and understand your own readings. It is not a substitute for a certified laboratory test, and nothing here is medical or regulatory advice. If a health parameter is out of range, confirm it with an accredited lab and speak to your water provider.