Chemical symbol/abbreviations:

Fe, Fe2+, Fe3+

Form commonly found in stormwater:

Dissolved iron as Fe2+ (ferrous iron) and Fe3+ (ferric iron), particulate iron

Adverse human impacts:

Although iron is an essential mineral, diseases of aging such as Alzheimer’s disease, other neurodegenerative diseases, arteriosclerosis, diabetes mellitus, and others have been linked to excess iron intake.[i]
Excess iron in drinking water can produce an unpleasant taste and stain home fixtures.[ii]

Adverse impacts on the environment:

Iron is an essential dietary mineral for fish and other animals as it is for humans.  Iron toxicity has been observed in certain fish species at concentrations in excess of 1,380 mg iron/kg in their diet.[iii]
Iron can also cause algae blooms, which create biological oxygen demand[iv] can kill fish, smother aquatic plants and produce potent neurotoxins.[v]

Even low concentrations of iron (0.1-1.0 mg/L) may cause nuisance algae species to replace inoffensive species[vi]

Stormwater Treatment to Remove Iron


Iron is white silvery metal that oxidizes quickly when coming into contact with water and oxygen. It is the fourth most abundant element in the earth’s crust, making up about 5% of its mass. It is soft, malleable, and strongly magnetic. Within humans and all other animals, iron plays a crucial role of carrying oxygen within the blood in the form of hemoglobin.1

Pure iron is not often used to manufacture products. Iron is much stronger and more useful when alloyed with carbon. Wrought iron and steel are examples of such iron alloys with carbon contents of 0.2 – 1.5%.[viii] Due to its abundance and mechanical strength, iron in the form of steel is used as a common building material for anything from bicycles to bridges.

In 2002, eleven open pit mines were responsible for supplying 99% of the iron ore produced in the United States. The U.S. produced 5% of the world’s iron supply while consuming about 7%.[ix] The world production of iron ore in 2004 was 1.4 billion tons. China, Brazil, and Australia generated 57% of the global production.[x]

U.S. EPA recommended water quality criteria:


Freshwater – Aquatic Organisms (Total Recoverable; pH 6.5-9.0)Saltwater– Aquatic OrganismsHuman Health for the consumption of
Acute (µg/L)Chronic (µg/L)Acute (µg/L)Chronic (µg/L)Water + Organism (µg/L)Organism Only (µg/L)

Iron is transported into the environment through water typically. It is naturally present in groundwater.[xi] However, drainage from abandoned mines can deliver toxic levels of iron into rivers and streams.[xii]
Elevated levels of iron in stormwater can be caused by rusting steel in constant contact with water.


[i] George Brewer, Risks of Copper and Iron Toxicity during Aging in Humans 23 Chem. Res. Toxicol. 2, 319–326 (Dec. 2009).

[ii] Illinois Dept. Public Health, Iron in Drinking Water (1999)

[iii] National Research Council Subcommittee on Fish Nutrition, Nutrient Requirements of Fish 19 (1993) available at

[iv] Florida Dept. of Environmental Protection, EcoSummary BioRecon Report, Camp Five Branch below Camp Five Landfill, Escambia County (Mar. 21, 2002) available at

[v] Queensland Univ. of Tech., Is Iron from Soil a Factor in Algae Blooms? ScienceDaily, Feb. 4, 2010,; Brandon Keim, Climate Quick Fix Could Create Toxic Algae Blooms, WIRED, Mar. 16, 2010,

[vi] Stephen Morton & Terrence Lee, Algal Blooms – Possible Effects of Iron 8 Environ. Sci. Technol. 7, 673 (1974) available at

[vii] U.S. EPA, National Recommended Water Quality Criteria, (last visited July 22, 2010).

[viii] HyperPhysics, Iron (last visited July 30, 2010).

[ix] MBendi Information Services, Inc., Iron Ore Mining in the United States – Overview (last visited July 30, 2010).

[x] U.S. Geological Survey, Minerals Commodity Summaries-Iron Ore (2005) available at

[xi] The Water Company, Common Water Problems and Their Corrections (last visited July 30, 2010).

[xii] Penn. Fish & Boat Commission, The Basics of Water Pollution in Pennsylvania, Penn. Angler & Boater 35 available at

The StormwateRx Aquip® industrial filtration system uses an innovative enhanced sand filtration process to effectively remove soluble and insoluble aluminum and other metals as well as oils, suspended solids, organics and nutrients from industrial stormwater runoff.

The Purus™ Stormwater Polishing System (previously known as the AquiPlus) provides the most advanced level of stormwater treatment, and is designed for challenging stormwater conditions or targeted pollutant removal.

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