Iron is a metal that accounts for about 5% of the Earth's crust and is the fourth most common element, but most of the Earth's iron is in the core of the planet not the crust.
Did You Know?
If the Earth did not have oxygen, we would not be living on a "Big Blue Ball", we would be living on a "Green Planet". Why? Not because of "Algae, but because of iron. Before the Earth became this wonderful big Blue Ball it was actually a big Green Ball. The water on the planet was green because of the very high levels of iron.
Iron is almost never naturally found as the metal; it is part of many compounds. Some of the more common iron compounds, of especial interest and relevance to drinking water, are the iron oxides. Where oxygen is limited, iron will oxidize to what is known as the ferrous cation (Fe++). When oxygen is abundant, it will oxidize to a higher oxidation state, to the ferric cation (Fe+++). Iron in the ferrous state is considerably more soluble in water than iron in the ferric state. If there is an abundant source of iron, groundwater with low oxygen can become saturated with ferrous iron. When that iron-saturated water is brought to the surface where oxygen-rich air can get to it, the ferrous iron becomes the much less soluble ferric iron, much of which promptly begins to precipitate as ferric hydroxide which has a bright red/orange/yellow color (iron stains).
A rather spectacular example of this is where there are mine outfalls (where the mine water comes to the surface) in coal-mining regions. Pyrite, an iron sulfide mineral, is associated with coal deposits. Coal mining breaks up the pyrite, exposing it to air and water, and when the pyrite oxides, the iron forms an iron oxide and the sulphur becomes sulfuric acid (the source of the acid in acid mine drainage). Should this happen in an underground coal mine that has been abandoned and flooded (low oxygen), the iron saturates the mine water with ferrous iron. Even with all of that dissolved ferrous iron in solution, the water remains clear (it would have a strong iron taste). The moment the mine reaches the surface and the oxygen in the air, the ferrous iron oxides to ferric iron and starts to precipitate. You can see what was clear water suddenly turn bright yellow/red/orange from the particles of precipitating ferrous hydroxide which form a gelatinous coating on the bottom and sides of the stream into which the mine outfall empties. On a much smaller scale, this is what happens when well water, loaded with ferrous iron, is pumped into your house and exposed to the air in your sink or washing machine.
Iron is typically a non-hazardous element that is a nuisance in a water supply rather than posing a specific health concern, but for some individuals iron can pose a health problem and concern. Iron and manganese are chemically similar and cause similar problems. Iron is the more frequent of the two contaminants in water supplies; manganese is typically found in iron-bearing water. Iron oxides can stain laundry, plates, and fixtures. Water percolating through soil and rock can dissolve minerals containing iron and hold them in solution. Occasionally pipe corrosion may be a source of iron in a drinking water source. Water with high levels of iron has a bad taste. Therefore, the primary problem with iron is that elevated levels can create aesthetic problems with the consumption and the use of the water.
In some private wells and even city water distribution systems, there are a number of "nuisance bacteria" that may contribute to an iron or aesthetic problem with your water. These nonpathogenic (not health-threatening) bacteria occur in soil, shallow aquifers, and some surface water. The bacteria use iron in their metabolic processes and/or create conditions that facilitate chemical corrosion within a drinking water source or distribution system. These bacteria form red-brown (iron oxide), black (iron oxide) or black-brown (manganese oxide) slime in toilet tanks and can clog water systems. If you are having problems with iron and/or occasional sulfur odors and slimy coatings, we recommend water testing that includes these Nuisance Bacteria.
For some individuals that are vulnerable to Iron Overload Disease or hemochromatosis, the iron in the water may present a specific health risk. Hemochromatosis can be an inherited genetic disorder that causes individuals to improperly process iron and be unable to flush the excess iron from their body. It can also be related to a deficient diet such as in a part of Africa where the people had a high iron intake coupled with a diet based mostly on corn. High levels of iron in the body can cause damage to the liver, bone/ bone marrow, thyroid, heart, and other glands/organs.
Iron Deficiency - Many of the symptoms of iron overload disease are similar to Iron Deficiency Anemia. The overlapping symptoms include fatigue, weakness and lack of energy. However, people with hemochromatosis generally experience a darkening of skin color (often referred to as bronzing), while those suffering from iron deficiency anemia will experience a pale skin color.
The Environmental Protection Agency (EPA) Standards for drinking water fall into two categories: Primary Standards and Secondary Standards. Primary Standards are based on health considerations and are designed to protect people from three classes of pollutants: pathogens, radioactive elements, and toxic chemicals. Secondary Standards are based on Taste, Odor, Color, Corrosivity, Foaming and staining properties of water. Iron and manganese are both classified under the Secondary Maximum Contaminant Level (SMCL) standards. Secondary drinking water standards may be regulated by your state. The SMCL for iron in drinking water is 0.3 mg/L milligrams per liter, sometimes expressed as 0.3 parts per million (ppm). The reason that the limit was set at that concentration is that it is the saturation limit for ferric iron. If water, typically well water, has a ferrous concentration of less than that, when the iron oxides to ferric iron upon exposure to air, the iron will remain in solution – the water stays clear, no precipitation, no iron staining. There should not be an unpleasant taste or odor either.
Unlike many contaminants in drinking water, iron is not potentially hazardous or a nuisance at a level or concentration that does not already impart a noticeable taste, odor, or color to the water. In most cases, iron lets you know there is a problem. You may have discolored water that appears yellow to red, reddish to brown staining, water that goes from clear to tinted, discolored laundry, staining on plates and porcelain surfaces, but you will know. The primary issue is that this may not be the only problem and the reason why iron is present may not be clear. Your best course of action is to get your water tested and compile as much information as possible about your water supply source, well construction, surrounding land-use, and local geology. In many cases, when you have a problem with iron you may also have corrosion, an elevated level of manganese or arsenic, a hardness issue, and an odor problem with the water. It is relatively easy to treat water for an iron problem, but it is necessary to have a complete analysis to determine the cause of the high iron level and any other problems associated with it before implementing a solution.
Level 1 Testing is done with simple observations that an individual can make with their own senses such as sight, smell, and taste. These observations can be readily apparent or can be observed as they change over time. In addition, accessible related information about the home can also be used to narrow down the cause of your water issues.
Unlike many contaminants, iron does present warning signs that you may have a problem with the water. The drinking water may appear discolored and the typical colors are reddish, yellow, and brown. In addition, the water may have a metallic or bitter taste and you may see settled material, or stains or coatings on porcelain fixtures.
Typically, it is the aesthetic problems associated with iron that is the first and only warning you may have a problem.
A problem with iron may come in many forms:
Level 2 Testing is Do-It-Yourself testing that can be done in your own home using a Testing Kit. After you’ve done Level 1 Testing, Level 2 Testing can confirm if your observations are correct. If your test results reveal the presence of a contaminant that is cause for concern, you can either proceed to determine the best treatment (see below) or continue to Level 3 Testing.
There are a number of low-cost screening tests for iron, but most individuals can see or taste something when there is an iron problem.
<div class="product-note in-L6-bromate">Note: If the concentration is < 0.01 mg/L</div>
<div class="product-note in-L4-methyl-tertiary">Note: Concentrations < 40 ppb</div>
<div class="product-note in-L6-mtbe-methyl-tert-butyl-ether">Note: If the concentration is < 0.07 mg/L (POU Device)</div>
<div class="product-note in-L6-tetrachloroethylene">Note: If the concentration is < 0.005 mg/L (POU Device)</div>
<div class="product-note in-L6-trichloroethylene">Note: If the concentration is < 0.004 mg/L (POU Device)</div>
<div class="product-note in-L6-toluene">Note: If the concentration is less than 0.8 mg/L</div>
<div class="product-note in-L6-alkalinity">Note: For High Hardness / Alkalinity</div>
<div class="product-note in-L6-benzene">Note: If the concentration is < 0.005 mg/L (POE Device)</div>
<div class="product-note in-L6-trichloroethylene">Note: If the concentration is < 0.004 mg/L (POE Device)</div>
<div class="product-note in-L6-chlorite">Note: If the concentration is < 0.8 mg/L (POE Device)</div>
<div class="product-note in-L6-bromate">Note: If the concentration is < 0.01 mg/L</div>
<div class="product-note in-L4-methyl-tertiary">Note: Concentrations < 40 ppb</div>
<div class="product-note in-L6-mtbe-methyl-tert-butyl-ether">Note: If the concentration is < 0.07 mg/L (POU Device)</div>
<div class="product-note in-L6-tetrachloroethylene">Note: If the concentration is < 0.005 mg/L (POU Device)</div>
<div class="product-note in-L6-trichloroethylene">Note: If the concentration is < 0.004 mg/L (POU Device)</div>
<div class="product-note in-L6-toluene">Note: If the concentration is less than 0.8 mg/L</div>
<div class="product-note in-L6-alkalinity">Note: For High Hardness / Alkalinity</div>
<div class="product-note in-L6-benzene">Note: If the concentration is < 0.005 mg/L (POE Device)</div>
<div class="product-note in-L6-trichloroethylene">Note: If the concentration is < 0.004 mg/L (POE Device)</div>
<div class="product-note in-L6-chlorite">Note: If the concentration is < 0.8 mg/L (POE Device)</div>
Level 3 Testing is done through an accredited Water Testing Laboratory. With Level 3 Testing, you can order a testing kit that is used to prepare your sample and submit it to the lab. By utilizing a lab, you have the assurance that a certified water expert had analyzed your water sample. If your test results reveal the presence of a contaminant that is cause for concern, you can either proceed to determine the best treatment options (see below) or continue to Level 4 Testing - Certified Testing.
Iron is not a common problem in city water unless it is associated with a corrosion problem in the home or distribution system. For city water sources, we recommend the City Water Basic Test and a Test for Corrosion. For Well Water and private water sources, iron is more common and we recommend the Well Water Check Basic with an Iron Bacteria Test. If you are looking for comprehensive testing, we recommend the Tap Score testing kits.
<div class="product-note in-L6-bromate">Note: If the concentration is < 0.01 mg/L</div>
<div class="product-note in-L4-methyl-tertiary">Note: Concentrations < 40 ppb</div>
<div class="product-note in-L6-mtbe-methyl-tert-butyl-ether">Note: If the concentration is < 0.07 mg/L (POU Device)</div>
<div class="product-note in-L6-tetrachloroethylene">Note: If the concentration is < 0.005 mg/L (POU Device)</div>
<div class="product-note in-L6-trichloroethylene">Note: If the concentration is < 0.004 mg/L (POU Device)</div>
<div class="product-note in-L6-toluene">Note: If the concentration is less than 0.8 mg/L</div>
<div class="product-note in-L6-alkalinity">Note: For High Hardness / Alkalinity</div>
<div class="product-note in-L6-benzene">Note: If the concentration is < 0.005 mg/L (POE Device)</div>
<div class="product-note in-L6-trichloroethylene">Note: If the concentration is < 0.004 mg/L (POE Device)</div>
<div class="product-note in-L6-chlorite">Note: If the concentration is < 0.8 mg/L (POE Device)</div>
A Level 4 Certified Test Test uses chain-of-custody with a water professional coming to your home to prepare the water sample and then works with an accredited laboratory in order to certify your test results. This type of testing not only gives you the highest level of assurance in the accuracy of your test results, but can also be used as a document in legal cases. For Baseline Testing, we recommend that you use Certified Testing.
If you are looking for certified testing for iron as part of developing a water quality treatment solution, it will be necessary to conduct a series of tests to provide enough information to design a treatment solution. If there is a concern that a surrounding activity or practice is causing the problem we also recommend ordering a Neighborhood Environmental Report. Elevated iron can be associated with a number of activities including petrochemical contamination.
For a drinking water system with an iron problem it is critical to get the water quality tested and confirm the form or state of the iron and what other contaminants are present in the water. If the water enters the home discolored, it may be possible to install a backwashable particle filter because most of the iron has already oxidized into a particle. If the water enters and it is only slightly discolored or appears clear and becomes discolored over time, it will be necessary to install either an oxidation filtration system or an ion-exchange system. These approaches are dependent on the chemistry and biological quality of your drinking water and both approaches will require performance evaluation, i.e., periodic testing, and maintenance.
In the short-term you can consider point-of-use devices to remove iron from the water or consider using a temporary water source. We do not recommend boiling the water. Even though boiling would cause the iron to oxidize and likely precipitate or settle out of the water, water with an iron problem may also contain elevated levels of manganese, arsenic, and other trace metals. Get a comprehensive water quality analysis and consider using either a point-of-use device or an alternative potable water source, like bottled water. If you are on a city water or well water source and the cause of the iron or discolored water is related to a bacterial growth or coating, it may be advisable to shock disinfect the source and/or piping.
<div class="product-note in-L6-bromate">Note: If the concentration is < 0.01 mg/L</div>
<div class="product-note in-L4-methyl-tertiary">Note: Concentrations < 40 ppb</div>
<div class="product-note in-L6-mtbe-methyl-tert-butyl-ether">Note: If the concentration is < 0.07 mg/L (POU Device)</div>
<div class="product-note in-L6-tetrachloroethylene">Note: If the concentration is < 0.005 mg/L (POU Device)</div>
<div class="product-note in-L6-trichloroethylene">Note: If the concentration is < 0.004 mg/L (POU Device)</div>
<div class="product-note in-L6-toluene">Note: If the concentration is less than 0.8 mg/L</div>
<div class="product-note in-L6-alkalinity">Note: For High Hardness / Alkalinity</div>
<div class="product-note in-L6-benzene">Note: If the concentration is < 0.005 mg/L (POE Device)</div>
<div class="product-note in-L6-trichloroethylene">Note: If the concentration is < 0.004 mg/L (POE Device)</div>
<div class="product-note in-L6-chlorite">Note: If the concentration is < 0.8 mg/L (POE Device)</div>
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In the long-term the problem with iron can be typically resolved after the cause for the condition has been documented and the chemistry and biological quality has been established. Common treatment systems for iron include: phosphate treatment (sequestration approach commonly used by city water sources), an ion-exchange water softener, oxidizing filters, aeration filtration systems, and chemical oxidation using a strong oxidizer.
These treatment techniques are effective in water that has an almost neutral pH (approximately 7.0). The phosphate compound treatment is an exception and is effective in the pH range of 5.0 to 8.0.
Phosphate treatment- Low levels of dissolved iron and manganese at combined concentrations up to 3 mg/l can be remedied using phosphate compound treatment. Phosphate compounds are a family of chemicals that can surround minerals and keep them in solution. Phosphate compounds injected into the water system can stabilize and disperse dissolved iron at this level. As a result, the iron and manganese are not available to react with oxygen and remain dissolved in the water. The phosphate compounds must be introduced into the water at a point where the iron is still dissolved in order to maintain water clarity and prevent possible iron staining. This should be before the pressure tank and as close to the well discharge point as possible. Phosphate compound treatment is a relatively inexpensive way to treat water for low levels of iron and manganese. Since phosphate compounds do not actually remove iron, water treated with these chemicals will retain a metallic taste. In addition, too great a concentration of phosphate compounds will make the water feel slippery.
Phosphate compounds are not stable at high temperatures. If phosphate compound-treated water is heated (for example, in a water heater or boiled water), the phosphates will break down and release iron and manganese. The released iron and manganese will then react with oxygen and precipitate.
Adding phosphate compounds is not recommended where the use of phosphate in most cleaning products is banned. Phosphate, from any source, contributes to excess nutrient content in surface water.
Ion exchange water softener-Low to moderate levels of dissolved iron, at less than 5 mg/L concentrations usually can be removed using an ion exchange water softener. Be sure to check the manufacturer's maximum iron removal level recommendations before you purchase a unit. Capacities for treating dissolved iron typically can range from 1 to 5 mg/L. Oxidized iron or levels of dissolved iron exceeding the manufacturer's recommendations will cause a softener to become plugged.
The principle is the same as that used to remove the hardness minerals, calcium and magnesium; i.e., iron in the untreated water is exchanged with sodium or potassium on the ion exchange medium. Iron is flushed from the softener medium by backwashing (forcing sodium-rich water back through the device). This process adds sodium to the resin medium, and the iron is carried away in the waste water.
Since iron removal reduces the softening capacity of the unit, the softener will have to be recharged more often. The manufacturer of the softener medium is able to make recommendations concerning the appropriate material to use for a particular concentration of iron. Some manufacturers recommend adding a "bed cleaning" chemical with each backwashing to prevent clogging.
Not all water softeners are able to remove iron from water. The manufacturer's specifications should indicate whether or not the equipment is appropriate for iron removal.
Water softeners add sodium or potassium to the water, a health concern for people on sodium-restricted diets and reduce the total hardness of the water. Consider installing a separate faucet to provide unsoftened water for cooking and drinking.
Oxidizing filter - An oxidizing filter treatment system is an option for moderate levels of dissolved iron and manganese at combined concentrations up to 15 mg/L. The filter material is usually natural manganese greensand or manufactured zeolite coated with manganese oxide, which adsorbs dissolved iron and manganese. Synthetic zeolite requires less backwash water and softens the water as it removes iron and manganese. The system must be selected and operated based on the amount of dissolved oxygen. Dissolved oxygen content can be determined by field test kits, some water treatment companies, or in a laboratory.
Aeration followed by filtration - High levels of dissolved iron and manganese at combined concentrations up to 25 mg/L can be oxidized to a solid form by aeration (mixing with air). For domestic water processing, the "pressure-type aerator" often is used.
In this system, air is sucked in and mixed with the passing stream of water. This air-saturated water then enters the precipitator/aerator vessel where the air separates from the water. From this point, the water flows through a filter where various filter media are used to screen out oxidized particles of iron, manganese, and some carbonate or sulfate.
The most important maintenance step involved in the operation is periodic backwashing of the filter. Manganese oxidation is slower than for iron and requires greater quantities of oxygen. Aeration is not recommended for water containing organic complexes of iron/manganese or iron/manganese bacteria that will clog the aspirator and filter.
Chemical oxidation followed by filtration - High levels of dissolved or oxidized iron and manganese greater than 10 mg/L can be treated by chemical oxidation, using an oxidizing chemical such as chlorine, followed by a sand trap filter to remove the precipitated material. Iron or manganese also can be oxidized from the dissolved to solid form by adding potassium permanganate, hydrogen peroxide, or Ozone to the untreated water. This treatment approach is particularly valuable when iron is combined with organic matter or when iron bacteria are present. I have done research using ozone and Ozone Iron and Manganese Removal is a great approach.
The oxidizing chemical is put into the water by a small feed pump that operates when the well pump operates. This may be done in the well, but typically is done just before the water enters a storage tank. A retention time of at least 20 minutes is required to allow oxidation to take place. The resulting solid particles then must be filtered out. When large concentrations of iron are present, a flushing sand filter may be needed for the filtering process.
If organic-complexed or colloidal iron/manganese is present in untreated water, a longer contact time and higher concentrations of chemicals are necessary for oxidation to take place. Adding aluminum sulfate (alum) improves filtration by causing larger iron/manganese particles to form.
When chlorine is used as the oxidizing agent, excess chlorine remains in treated water. If the particle filter is made of calcite, sand, anthracite or aluminum silicate, a minimum quantity of chlorine should be used to avoid the unpleasant taste that results from excess chlorine. An activated-carbon filter can be used to remove excess chlorine and small quantities of solid iron/manganese particles.
Any filtration material requires frequent and regular backwashing or replacement to eliminate the solid iron/manganese particles. Some units have an automatic backwash cycle to handle this task.
The ideal pH range for chlorine bleach to oxidize iron is 6.5 to 7.5. Chlorination is not the method of choice for high manganese levels since a pH greater than 9.5 is required for complete oxidation. Potassium permanganate will effectively oxidize manganese at pH values above 7.5 and is more effective than chlorine oxidation of organic iron if that is a problem.
Potassium permanganate is poisonous and a skin irritant. There must be no excess potassium permanganate in treated water and the concentrated chemical must be stored in its original container away from children and animals. Careful calibration, maintenance, and monitoring are required when potassium permanganate is used as an oxidizing agent.
<div class="product-note in-L6-bromate">Note: If the concentration is < 0.01 mg/L</div>
<div class="product-note in-L4-methyl-tertiary">Note: Concentrations < 40 ppb</div>
<div class="product-note in-L6-mtbe-methyl-tert-butyl-ether">Note: If the concentration is < 0.07 mg/L (POU Device)</div>
<div class="product-note in-L6-tetrachloroethylene">Note: If the concentration is < 0.005 mg/L (POU Device)</div>
<div class="product-note in-L6-trichloroethylene">Note: If the concentration is < 0.004 mg/L (POU Device)</div>
<div class="product-note in-L6-toluene">Note: If the concentration is less than 0.8 mg/L</div>
<div class="product-note in-L6-alkalinity">Note: For High Hardness / Alkalinity</div>
<div class="product-note in-L6-benzene">Note: If the concentration is < 0.005 mg/L (POE Device)</div>
<div class="product-note in-L6-trichloroethylene">Note: If the concentration is < 0.004 mg/L (POE Device)</div>
<div class="product-note in-L6-chlorite">Note: If the concentration is < 0.8 mg/L (POE Device)</div>
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