Chromium in water: chromium III, chromium VI, risks, regulation and filtration
Chromium is a metal naturally present in certain rocks and minerals. It is also used in the manufacture of stainless steel, metal alloys, chrome plating, pigments, leather tanning and various industrial processes. In water, chromium can mainly exist in the trivalent form Cr(III) or the hexavalent form Cr(VI). These two forms have neither the same chemical behavior nor the same level of toxicity.
- Chemical symbol
- Cr
- Atomic number
- 24
- Main forms
- Cr(III) and Cr(VI)
- Current EU value
- 50 µg/L
What is chromium?
Chromium is a chemical element with the symbol Cr and atomic number 24. It is a hard metal that is naturally present in the Earth's crust, mainly in chromite ore.
Metallic chromium is valued for its corrosion resistance, hardness, and shiny appearance. In the environment, however, it is generally not present as pure metal, but in the form of chemical compounds with different oxidation states.
Keep in mind: an analysis indicating only "total chromium" does not necessarily reveal the proportion of chromium III and chromium VI present in the sample.
What is the difference between chromium III and chromium VI?
Chromium can exist in several oxidation states. In water and natural environments, the most significant forms are trivalent chromium Cr(III) and hexavalent chromium Cr(VI).
| Form | Notation | General behavior | Health concern |
|---|---|---|---|
| Trivalent chromium | Cr(III) | Generally less mobile in water and more likely to bind to soil, particles and sediments. | Generally less toxic than Cr(VI), but significant exposure can nevertheless cause adverse effects. |
| Hexavalent chromium | Cr(VI) | Often more soluble and more mobile under certain environmental conditions. | More toxic and more easily absorbed by cells. It is particularly concerning in professional and environmental contexts. |
pH, oxidation-reduction conditions, the presence of iron, manganese, organic matter, and other substances can promote the transformation of one form into another.
The toxicity and effectiveness of a treatment should not be inferred solely from a total chromium measurement. A separate analysis of Cr(VI) may be necessary when this form is suspected.
What is chromium used for?
Chromium is widely used in industry due to its corrosion resistance, hardness, color, and chemical properties.
- manufacture of stainless steel and metal alloys;
- decorative or anti-corrosion chrome plating of metal surfaces;
- manufacture of pigments for paints, inks, plastics and ceramics;
- leather tanning, mainly with chromium III compounds;
- treatment and protection of certain metal surfaces;
- production of refractory materials;
- chemical industry and catalyst manufacturing;
- former wood preservation treatments containing chromium.
Chromium VI compounds are subject to significant restrictions due to their toxicity. Their use is regulated in many industrial sectors.
How does chromium get into water?
Geological origin
The natural weathering of certain rocks and ores containing chromium can release small amounts of chromium into soils, streams or groundwater.
Metallurgical industries
Steel manufacturing, surface treatment, chrome plating and alloy production can generate effluents or waste containing chromium.
Tanneries
Leather tanning mainly uses chromium III compounds. Poor management of effluents and waste can lead to soil and water contamination.
Pigments and chemical industries
Certain paints, pigments and various chemical processes can be sources of chromium, particularly around former industrial sites.
Contaminated sites and waste
Landfills, mining residues, industrial sludge or historically contaminated soils can continue to release chromium long after the initial activity has ceased.
What are the health risks of chromium?
The effects depend heavily on the chemical form of chromium, the concentration, the route of exposure and its duration.
Chromium VI
Hexavalent chromium is the most concerning form. Professional inhalation exposure is associated with respiratory cancers. It can also cause irritation, ulceration, skin reactions and damage to different organs depending on the level and route of exposure.
Possible effects of significant or prolonged exposure may include:
- irritation of the skin and mucous membranes;
- allergic dermatitis;
- digestive system damage;
- kidney or liver damage;
- respiratory effects during inhalation exposure;
- increased risk of cancer in certain chromium VI exposure contexts.
Chromium III
Chromium III is generally less toxic and less mobile than chromium VI. However, it should not be considered completely harmless: high concentrations or certain chemical forms can cause adverse effects.
Hazard classifications established for professional inhalation exposure cannot be applied directly, without nuance, to ingestion exposure through drinking water. The route of exposure and the chemical form must always be specified.
What are the effects of chromium on the environment?
Chromium does not degrade like organic substances. It can change its oxidation state, bind to particles, precipitate, dissolve or be transported in water.
Chromium VI is generally more mobile and more toxic to aquatic organisms than chromium III. However, the effects depend on the concentration, pH, water hardness and the characteristics of the environment.
Contamination can affect microorganisms, plants, invertebrates and fish. Sediments can also act as a long-term reservoir for chromium.
What is the chromium limit for drinking water?
The European Directive provides for a parametric value of 25 µg/L for chromium. This value must be met no later than January 12, 2036. Until that date, the applicable parametric value may remain set at 50 µg/L.
| Reference | Value | Details |
|---|---|---|
| European Union – until January 12, 2036 | 50 µg/L | Transitional parametric value provided by the European directive. |
| European Union – by January 12, 2036 at the latest | 25 µg/L | New parametric value to be met at the end of the transitional period. |
| World Health Organization | 50 µg/L | Provisional guideline value for total chromium in drinking water. |
| United States – EPA | 100 µg/L | Maximum regulatory concentration for total chromium, including chromium III and chromium VI. |
Regulations generally apply to total chromium. A value for total chromium should not be interpreted as a value specific to chromium VI.
How can I tell if water contains chromium?
Chromium present at trace levels generally cannot be identified by the taste, odor, or appearance of the water. Laboratory analysis is required.
Depending on the context, the laboratory can measure:
- total chromium;
- dissolved chromium;
- hexavalent chromium Cr(VI);
- trivalent chromium Cr(III), directly or by difference;
- chromium associated with particles or sediments.
Chromium speciation can change after sampling. The choice of bottle, preservation, pH and the time before analysis must therefore comply with the laboratory protocol.
What technologies can reduce chromium in water?
Treatment depends on the chemical form of chromium. Cr(III) and Cr(VI) are not necessarily removed with the same level of effectiveness.
Processes that can be used include:
- reduction of Cr(VI) to Cr(III), followed by precipitation and filtration in certain installations;
- certain specialized adsorbent media;
- certain ion exchangers;
- properly sized and maintained reverse osmosis;
- coagulation, precipitation and filtration;
- certain iron-based media or other materials specifically designed for chromium;
- treatment or removal of the contamination source.
Not all activated carbon filters automatically reduce chromium, and a reduction in total chromium does not necessarily demonstrate the same effectiveness for each of its forms. You must verify the contaminant, the form tested, and the precise conditions of the report.
When actual contamination is confirmed, water analysis before and after treatment is recommended. Periodic checks allow for verifying the system's effectiveness during its use.
Imperial test results for chromium
Chromium is listed in the performance analysis table published for Monderma Imperial GF and Imperial AMB filters. The tests were conducted by Envirotek Laboratories in the United States.
Chromium: result indicated in the Envirotek table
Interpretation limit: the "Chromium" line does not specify on its own whether the contaminant tested was exclusively chromium III, chromium VI, or a mixture measured as total chromium. The result should therefore not be presented as distinct proof of Cr(VI) reduction without additional documentation.
The laboratory performance results correspond to the conditions of the test protocol. Real-world results may vary depending on pH, the form of chromium, water composition, initial concentration, flow rate, contact time, maintenance, and the duration of cartridge use.
A test conducted according to an NSF/ANSI protocol does not necessarily mean that the entire filter is NSF-certified for chromium reduction. Official certifications and performance tests must be distinguished.
View Monderma certifications and analysesFrequently asked questions about chromium in water
What is the difference between chromium III and chromium VI?
Chromium III and chromium VI are two different oxidation states. Chromium VI is generally more mobile and toxic. Their behavior and treatment can therefore be different.
Is chromium in water always chromium VI?
No. Water may contain chromium III, chromium VI, or different forms simultaneously. A total chromium analysis does not necessarily reveal their distribution.
What is the European limit for chromium in drinking water?
The transitional value is 50 µg/L. The 25 µg/L limit must be met no later than January 12, 2036.
Can you see or smell chromium in water?
No. At concentrations typically found in drinking water, its presence cannot be reliably determined by taste, odor, or color.
Does boiling water remove chromium?
No. Domestic boiling does not remove dissolved chromium. The loss of water through evaporation can even increase the concentration in the remaining volume.
Does an activated carbon filter always remove chromium?
No. Performance depends on the media used, the form of chromium, pH, flow rate, and test conditions. A specific report must be consulted.
How can I check for the presence of chromium VI?
You must request a specific hexavalent chromium analysis. A simple measurement of total chromium does not always make it possible to determine the exact Cr(VI) concentration.
Related contaminants
Chromium belongs to the category of metals and trace elements. You can also consult the other fact sheets dedicated to metallic contaminants that may be present in water.
Scientific and administrative sources
This fact sheet is based on public agencies, international institutions, and government scientific databases. No commercial blogs, comparison sites, or affiliate sites are used as primary health sources.
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World Health Organization – Chromium in drinking water
Information on the presence of chromium, its chemical forms, its
health effects, and the provisional guideline value.
View official WHO fact sheet -
World Health Organization – Chromium background document
Detailed assessment of the behavior of chromium III and chromium VI in
water and available health data.
View WHO scientific document -
European Union – Directive (EU) 2020/2184
Official text setting the parametric value of 25 µg/L no later than
January 12, 2036, and the transitional value of 50 µg/L.
View directive on EUR-Lex -
Environmental Protection Agency – Chromium in drinking water
Official information on the US federal standard of 100 µg/L
for total chromium.
View official EPA page -
EPA – National primary drinking water regulations
Official table of regulated contaminants and their limits.
View EPA regulations -
PubChem – National Institutes of Health
Data on the element chromium, its symbol, atomic number, and general
properties.
View PubChem entry -
Monderma – Certifications and laboratory analyses
Certifications, reports, and analysis table for Imperial filters.
View Monderma certifications and analyses
