2 WQA Chromium Fact Sheet_20170726

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Contaminant
In Water As
Maximum Contaminant Level
US EPA (for total Chromium):
Chromium (Cr)
Trivalent Cr(III): Cr3+
MCL* = 0.10 mg/L (or ppm)
Hexavalent Cr(VI) dichromate Cr2072-
MCLG** = 0.10 mg/L
Hexavalent Cr(VI) chromate Cr042-
WHOt Guideline = 0.05 mg/L
California MCL:
Cr-6 = 0.010 mg/L
Total Cr = 0.05 mg/L
Sources
Trivalent chromium is naturally occurring
Hexavalent chromium is produced by certain chemical processes
Nausea, gastrointestinal distress, stomach ulcers, skin ulcers, allergic reactions
Potential Health
Kidney and liver damage
Effects
Reproductive problems
Lung and nasal cancer
Trivalent
Reverse Osmosis (TFC, CTA)
Distillation
Strong Acid Cation Resin
Hexavalent
Treatment Methods
Reverse Osmosis (TFC, CTA)
Point -of -Entry
Distillation
Point -of -Use
Strong Base Anion Resin
Weak Base Anion Resin
Organic Complexes
Reverse Osmosis (TFC, CTA)
Activated Carbon
*Maximum Contaminant Level (MCL) — The highest level of a contaminant that is allowed in drinking water. MCLs are set as close to
MCLGs as feasible using the best available treatment technology and taking cost into consideration. MCLs are enforceable standards.
**Maximum Contaminant Level Goal (MCLG) - The level of a contaminant in drinking water below which there is no known or expected risk
to health. MCLGs allow for a margin of safety and are non -enforceable public health goals.
WHOt - World Health Organization
Trivalent chromium occurs naturally in the environment and can be found in rocks and soil. It can
also be found in fruits, vegetables and meat. Cr" is used to make bricks, metal alloys and chemical
compounds. Hexavalent chromium does not occur naturally in the environment. It is produced by

WQA Technical Fact Sheet: Chromium
certain chemical processes and is considered toxic. Metallic elemental chromium or chrome does not
occur naturally in the environment. It is used to make steel and other metal alloys and is produced from
chrome bearing ore.
HEALTH EFFECTS
It is suggested that Cr3+ is not considered a significant health risk, while the more soluble Cr" is
considered toxic. Two of the more common forms of this type of hexavalent chromium are dichromate
(Cr207_2), found at a pH below 5, and chromate (Cr04 2), found at a pH above 6. Cr6+ thus forms
negatively charged anionic complexes. Cr6+ is used in the plating industry, paint production, as well as
an anticorrosive alloy in steel and iron production. Cr6+ was also used as an anti -corrosion agent in
boiler water and cooling tower water treatment. It is considered a health risk whether it contacts the
skin, it is inhaled, or it is ingested. It can cause nausea, gastrointestinal distress, stomach ulcers, skin
ulcers, allergic reactions, kidney and liver damage, reproductive problems, lung and nasal cancer. It is
believed that hexavalent chromium (Cr6+) will be reduced to Cr3+ causing DNA damage in the cell. It is
possible, under the right chemical environment for chromium to convert between the different forms.
The EPA has set a maximum contaminant level (MCL) and the MCLG for total chromium of 0.1 ppm
(100 ppb) in drinking water. The USEPA is currently evaluating to determine if a new drinking water
standard for hexavalent chromium, Cr" is needed. Tap water has an average of 0.4 to 8 ppb total
chromium; air has an average of 0.1 ppb (OSHA has set a workplace indoor air limit of 100 ppb based
on a 40 hour workweek). Soil has an average chromium value of 400 ppm.
TREATMENT METHODS
Trivalent
Reverse Osmosis (TFC, CTA)
Distillation
Strong Acid Cation Resin
Hexavalent
Residential
Point -of -Use
Reverse Osmosis (TFC, CTA)
Point -of -Entry
Distillation
Strong Base Anion Resin
Weak Base Anion Resin
Organic Complexes
Reverse Osmosis (TFC, CTA)
Activated Carbon
Reduce Cr(VI) to Cr(III), with chemical means such
Municipal
as reaction with ferrous iron, followed by coagulation
and filtration

Trivalent chromium is a cation and can be removed from water with a strong acid cation ion -
exchange resin in the sodium form. Salt (NaCI) is used as the regenerant, however chromium may not
be completely removed from the resin during the regeneration process. A periodic acid strip will help
remove Cr3+ from the resin, followed by a normal salt regeneration to convert the resin to the sodium
form. A second regeneration may be necessary if the pH of the service cycle is too low. Acid stripping
may be done at a regeneration plant, however, consumers could use a resin cleaner, as with iron, or
add % cup of citric acid per bag of salt once every 3 months. In general, cation resins will have a higher
affinity for chromium than for manganese and iron, therefore iron and manganese will break through
before chromium does. Consult with the resin manufacturer for specific chromium loads on the resin
bed and regeneration recommendations.
Hexavalent chromium can be removed from water by a number of methods. A strong base anion
exchange system will reduce both dichromate and chromate. The resin is regenerated with salt,
however an occasional treatment of a combined salt and caustic solution will be required since a
portion of the chrome will not be stripped from the resin. The service cycle can be extended if the pH of
the raw water is less than 5. A weak base anion resin can also be used if proper pretreatment and
regeneration are used; treatment designers should consult their resin manufacturer for details.
Chromate is an oxidizer and will attack and breakdown ion exchange resin over time. Resin should not
be stored or shutdown when the resin is in the chromate form. Heat may also be generated which can
have a negative impact on the resin.
Organic complexes of chromium can be reduced with a combination of reverse osmosis and
granular activated carbon.
Reverse osmosis and distillation will reduce all types of chromium found in water. Proper
pretreatment for hardness, iron, manganese, and silt or turbidity control is required for successful and
trouble free results.
The treatment methods listed herein are generally recognized as techniques that can effectively
reduce the listed contaminants sufficiently to meet or exceed the relevant MCL. However, this list does
not reflect the fact that point-of-use/point-of-entry (POU/POE) devices and systems currently on the
market may differ widely in their effectiveness in treating specific contaminants, and performance may
vary from application to application. Therefore, selection of a particular device or system for health
contaminant reduction should be made only after careful investigation of its performance capabilities
based on results from competent equipment validation testing for the specific contaminant to be
reduced.
As part of point -of -entry treatment system installation procedures, system performance
characteristics should be verified by tests conducted under established test procedures and water
analysis. Thereafter, the resulting water should be monitored periodically to verify continued
performance. The application of the water treatment equipment must be controlled diligently to ensure
that acceptable feed water conditions and equipment capacity are not exceeded.
Visit WQA.org to locate water professionals in your area. Note that Certified Water Specialists have
passed the water treatment education program with the Water Quality Association and continue their
education with recertification every 3 years.

REGULATIONS
In the United States, the EPA under the authority of the Safe Drinking Water Act (SDWA) has set the
Maximum Contaminant Level (MCL) and the MCL Goal (MCLG) for chromium at 0.10 mg/L. This is the
health -based level at which no known or anticipated adverse effects on human health occur and for
which an adequate margin of safety exists. This means that utilities must ensure that water from the
customer's tap does not exceed this level in at least 90 percent of the homes sampled. The utility must
take certain steps to correct the problem if the tap water exceeds the limit and they must notify citizens
of all violations of the standard.
In the state of California, the MCL is 0.05 mg/L for total chromium in drinking water. Specifically for
chromium-6, California has finalized the public health goal (PHG) at 0.02 ppb and has newly adopted a
MCL for Cr-6 which is 10ppb. Additionally, total chromium and chromium-6 are on the US EPA's List 1
for assessment according to the Unregulated Contaminant Monitoring Rule (UCMR).
REFERENCES/SOURCES
California Department of Public Health (August 23, 2013). "Chromium-6 in Drinking Water: MCL Update".
Retrieved from http://www.cdph.ca.gov/certlic/drinkin-qwater/Pages/Chromium6.aspx.
US EPA (May 21, 2012). "Basic information about chromium in drinking water". Retrieved from
http://water.epa.gov/drink/contaminants/basicinformation/chromium.cfm.
US EPA. "Technical Factsheet on: Chromium". Retrieved from
http://www.epa.gov/safewater/pdfs/factsheets/ioc/tech/chromium.pdf.
USEPA (May 2012). "The Third Unregulated Contaminant Monitoring Rule: Searching for Emerging Contaminants
in Drinking Water". Retrieved from
htta:/./water.eoa.gov/lawsreos/ruiesregs/sdwa/ucmr/ucmr3/ur)load/UCMR3 Factsheet General.pdf.
WHO (2003) Chromium in drinking -water. Background document for preparation of
WHO Guidelines for drinking -water quality. Geneva, World Health Organization
(WHO/SDE/WSH/03.04/4).

ACKNOWLEDGEMENT
WQA wishes to express sincere appreciation for the unselfish
contributions of the members of WQA who contributed their
time and expertise toward the completion of this bulletin.
The Water Quality Association publishes this Technical
Application Bulletin as a service to its members and the
interested public. Information contained herein is based upon the
most recent public data known as of the publication date and
cannot take into account relevant data published thereafter. The
Water Quality Association makes no recommendations for the
Arvind Patil, Ph.D., CWS-I
Richard Andrew selection of a treatment system, and expressly disclaims any
Gary Hatch, Ph.D.
Shannon Murphy responsibility for the results of the use of any treatment method
Charles Michaud, CWS-VI
Mark Brotman, CWS-VI
Steve VerStrat
Pauli Undesser, M.S., CWS-VI or device to reduce or remove a particular contaminant.
P. Regunathan, Ph.D.
Kimberly Redden, CWS-VI
Rebecca Tallon, P.E.
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