Elevated levels of iron (often called "rust") is a common water quality issue for many well owners. The fact that iron makes up five percent of the earth's crust and elementary iron readily dissolves in groundwater is one of the reasons it is so prevalent in wells. Iron is dissolved from the rocks and minerals that form aquifers. Generally, the longer the groundwater is underground and flowing through cracks, crevices, and pores, the higher the concentration of iron is likely to be.
Is Iron Harmful?
Actually, iron is beneficial to humans and is a necessary nutrient in most diets. The US Environmental Protection Agency (EPA) does not consider elevated iron concentrations in drinking water to be a health problem. However, most people get their daily minerals and vitamins through the food they eat and not the water they consume. Water is not a significant source of iron.
So, while iron may not be a problem from a consumption standpoint, it can be very detrimental to everything your water touches, including pipes, faucets, fixtures, washing machines, dishwashers, showers, tubs, clothing, dishes, and silverware. Iron typically stains everything that it touches a brown, red, or yellow color (depending upon the level), and has been known to clog or plug pipes, solenoids, nozzles, faucet aerators, and many other things, this leads to the need for scientifically back iron removal solutions.
The EPA considers iron in well water as a secondary contaminant, which means it does not have a direct impact on health. The Maximum Contaminant Level set out by the EPA is 0.3 milligrams per liter (mg/l), but this is merely a guideline and not a federal standard.
Where to Start
The first step in proper iron removal is to determine if the iron is in particle form (oxidized state) or dissolved (reduced state). What color is the water when you first draw all glass? The color of the water is an initial clue as to the presence of oxidized iron. Iron, which is oxidized, forms small "rust" particles that can give the water running out of a faucet a red, brown, or yellow color. Oxidized iron needs to be removed with a sediment filter that will catch the small particles down to approximately five (5) microns before they pass into the home plumbing and/or other water conditioning equipment.
If you have dissolved or "clear water" iron, it may become oxidized once it is exposed to oxygen in the air. Agitating the water or adding oxidants such as chlorine bleach or other home cleaners containing chlorine can accelerate this process. As the water becomes oxidized, it can stain plumbing fixtures and clothes. To help prevent problems with iron staining, the EPA has recommended that your water should contain no more than 0.3 parts per million (ppm or milligrams per liter [mg/L]) dissolved iron.
If you have an old-style galvanized pressure tank, it is an excellent idea to replace it with a bladder-type pressure tank that separates the air from the water (with the bladder) and oxidizes the iron with the oxygen in the air. There are few galvanized tanks in use, as most have been replaced with bladder tanks, but if you are the lucky owner of one, you should quickly replace it, especially if your well water has iron.
Get a Detailed Laboratory Water Analysis
Before you even start to consider what type of system you may need to treat your iron, in addition to determining what type of iron you may have and whether it is IRB or SRB, you absolutely need to get a detailed water analysis, such as you may find on MyTapScore.
It is imperative that you get a detailed water test from independent third-party laboratories that have no interest in selling equipment – just testing your water accurately. Due to the sheer volume of tests that we offer to our customers, we sell these same tests at a big discount due to our volume purchasing.
When providing water treatment solutions, it is imperative that we precisely know what is in your water, including "competing contaminants. That is the only way to know what kind of iron removal system can be used to solve your iron problem. Then, we can guarantee that solution to work. If you have dissolved or "clear water" iron or even ferric iron, there are several treatment methods you may consider. One final note: Removing manganese and/or sulfur is similar to removing iron. The process is the same but there are a few differences.
Iron Removal Systems
Over the years water treatment companies have developed a number of different iron removal methods and systems. Let's take a look at the most popular types and weigh in on the pro and cons of each system.
If you have iron concentrations of .3 ppm to approximately 3.0 ppm, water softeners that use salt can frequently be effective. The sodium resins in these systems actually prefer the iron to the "hardness" elements such as calcium and magnesium. There are two caveats here: (1) You should test the water to determine if you have iron sulfur-reducing bacterial – IRB or SRB. If you do, then a water softener will not work for very long as the bed often gets overwhelmed with the bacteria; and (2) It will work the best if the pH is as close to neutral (7.0) as possible. Interestingly, IRB and SRB usually occur in water supplies that have a pH above 7.4.
If the iron concentrations are greater than 3.0 ppm of iron, then the treatment must be specially designed to ensure that the "backwash" regeneration cycle is strong enough the remove and wash away the iron that is collected out of the raw water. While not recommending that a water softener be installed on the water above 3.0 ppm, it will work as long as the pH is as close to 7.0 as possible (or even lower). If you do intend to remove iron with a water softener, then it is advisable that you use a twin-tank system.
Kinetico® pioneered this concept and today, twin-resin tank water softeners are very common. They work better with iron because they fill the brink tank with soft water (many others do that as well) and regenerate with soft water. No single resin tank can accomplish that. With a twin-tank water softener, one tank is always in service, while the other one is on standby or regenerating. Therefore it regenerates at precisely the right time, with the precise amount of salt, and with the superior resin-cleaning capability of soft water.
If you use a water softener to remove iron, I would recommend that you use Iron Out" Salt, such as one of the following:
Red-Out Dura Cube
Diamond Crystal Iron Fighter
Morton Rust Remover
Pro's Pick Red-Out Solar Salt
We also recommend the use of a resin cleaner, such as ResKleen™ or Iron Out®. You should use one or the other, but not both.
If your iron levels are lower (0.3 ppm to 3.0 ppm) then this is the most economical way to remove iron. However, you may use a lot of salt, and you need to be diligent with using resin cleaner and at least once a month, you should "super-regenerate" your softener resin tank(s) by pouring three or four (4) gallons of warm water into your salt tank and immediately regenerating the softener. This will keep the resin bed in great condition. FYI: every gallon of water dissolves about 3 pounds of salt, so you will use an additional nine to twelve pounds of salt, but it is one of the best things you can do for a water softener.
Beware of water softeners who claim that they have special resin that removes iron. They may work for a while, but things that sound too good to be true, usually are. So buyer beware. We sell our systems all over the USA, so we tend toward "overkill" than "underkill." We want to make sure we eradicate all the iron, and we like "fail-safe" solutions.
Oxidation Iron Removal Systems
If you have higher concentrations of dissolved iron, then your well water will require more aggressive oxidation treatment such as with aeration, chlorine, Hydrogen Peroxide, Potassium Permanganate, or Ozone. Each of these methods converts dissolved iron into ferric (oxidized) iron that can be trapped by a filter. In the case of aeration, it adds oxygen to the water, which oxidizes the iron, and then the water is filtered at the end of the aeration process.
There are three common chemicals that are used for the oxidation of iron, those being chlorine, potassium permanganate, and hydrogen peroxide. These chemicals are injected into the water system, where they begin oxidizing the iron. They all involve chemical injection systems:
Chlorine Based Iron Removal Systems
With a chlorine injection system, a contact tank that will provide twenty (20) minutes of contact time is essential. Therefore, if you have a peak flow rate of 10 gallons per minute, you would need 200 gallons of storage capacity (10 GPM X 20 minutes = 200 gallons. You can inject the chlorine ahead of a pressure tank followed by a contact tank, in which case, the injection system would be wired to the well pump's pressure switch, and the chlorine injection would occur before the pressure tank and the contact tank.
In this application, you would not need a proportional injection system because when the pump runs, it is always at approximately the same rate. In the above case, you may want to use a 120-gallon pressure tank and a 120-gallon retention or contact tank. You could also use any size pressure tank, as long as you had close to the 200-gallon retention capacity. You can circumvent the amount of storage needed with one of the new Baffle-Type Fiberglass Tanks (which also will not rust) and require about half the space. In the above example, an 80-gallon retention tank and 40-gallon pressure tank would more than suffice, as long as you injected the chlorine ahead of the pressure
In the retention tank, the chlorine oxidizes the iron causing it to precipitate out. The precipitate and the residual chlorine are then filtered out by a granular activated carbon (GAC) filter. Again, the carbon filter needs to be sized so that there is prolonged contact and the chlorine is completely removed. Five (5) GPM per cubic foot of carbon is the flow rate that should not be exceeded, so in the instant case, you would need at least two cubic feet of GAC in a 12" x 52" tank in order to accommodate that flow rate. It is imperative to have an adequately sized GAC filter in order to fully remove the chlorine as well as any disinfection by-products (DMP's).
Pros & Cons:
Chlorine is a great disinfectant but is not a good oxidizer, thus the contact time in the retention tank. Be prepared to clean out the bottom of the retention tank periodically. Additionally, with cold well water, chlorine frequently crystallizes at the injection point, and it plugs shut. You will need to become an expert at cleaning the injection fitting. Overall, if your iron is not over 8 ppm, chlorine injection can be an economical method of removing iron from your well water.
Potassium Permanganate Based Iron Removal Systems
For many years, potassium permanganate has been a routine method of treating water for iron. Most older iron filters utilized potassium permanganate to regenerate manganese greensand. Greensand is manufactured from glauconite, which is a green clay mineral that contains iron and has ion-exchange properties. Greensand is able to absorb iron and manganese.
As water passes through the greensand filter, soluble iron and manganese are pulled from the solution and later react to form insoluble iron and manganese. Regular backwashing is required to remove the insoluble forms of iron and manganese. Also, someone must regenerate the greensand filter periodically with a potassium permanganate solution. Potassium permanganate is a material that, when mixed with water, turns a deep, dark purple and stains anything it touches. It requires a pH of above 7.0 and is generally sufficient for up to 10 ppm of iron.
Pros & Cons:
Due to the staining issues, potassium permanganate is no longer considered to be a viable oxidizer by many people, although it is still popular among municipalities. It also does not perform well at high levels of iron in many residential applications.
Aeration Based Iron Removal Systems
Of course, Oxygen (O2) is a component of air, and the oxygen in the air is a good oxidizer of iron, sulfur, and manganese. It seems that these days everyone in the water treatment business is selling an air-injection iron filter. They market these as "chemical-free iron filters," and some do work... at least for a few weeks or months unless you have very high iron (typically over 8-10 ppm). Then they may fail sooner. If you have "low to moderate" iron, they may work for a while, but many are doomed to failure in the long-term.
Companies who build these "air-injection iron filters" utilize a water softener control valve, which uses a "nozzle and venturi" assembly (commonly called an "educator" or "injector"). This creates a vacuum that is used to draw saltwater (commonly called brine) into a media tank (usually containing cation-exchange softening resin). In this case, there is no brine tank, and the injector is just drawing air. Under ideal conditions, a "head of air" forms at the top of the tank. This is typically enough air to last one or two days, but if you use a lot of water, it will deplete the air too fast.
Some companies use contact tanks and air pumps to keep the air in the tank to oxidize the iron properly, and while they do work, they are noisy and problematic. As I mentioned, we cannot sell products that require a lot of services, so we shy away from these types of products.
Instead of resin in the tank, these companies utilize media like Birm, Filox, Katalox, Pyrolox, or Catalytic Carbon, which provides an area for iron to oxidize. Instead of brine, the water softener valve draws air (which contains oxygen) into the media tank, where it oxidizes the iron (allegedly).
That's how it works, and it really sounds great, doesn't it?
Pros & Cons:
Here's the problem: to remove iron, it has to be oxidized - 100% oxidized! The iron is not fully oxidized, so it forms a tremendous amount of "iron sludge." This sludge fouls the media, coats the surfaces, and plugs the injector so that it can no longer draw air through its eductor. Then, the iron that has accumulated in the media and internal parts (and plugged the injector) continues to build up. The system is overwhelmed with iron sludge and ceases to work. If you think I am making this up, check out this picture that was taken in an actual application after one year on just two(2) ppm of iron:
A great deal of iron sludge accumulates around the top of the tank, the value, and the distributor. The media itself eventually becomes overwhelmed by the sludge.
Within a few months, the eductor (injector) is plugged with iron sludge, and the water softener control value quits drawing air. The iron continues to build up, and soon after that, the system is overwhelmed. Sometimes it simply shuts down from sludge, and the flow is greatly impacted.
Most of the time, you just start noticing iron stains, and by the time you do something about it, it's too late. There's one way to make sure your air injection system doesn't stop working, and that is to disassemble the valve every 3-6 months. You will need to clean the parts with chlorine or sodium hydrosulfite and sodium metabisulfite in order to make sure to clean the injector assembly to allow it to function correctly. It's probably a good idea to clean out the media with chlorine or sodium hydrosulfite and sodium metabisulfite as well.
Now, if that seems like a lot of work, it is. So, some customers add on a room to their home and let their local water treatment company technician live there (OK, that's just sarcasm, but you get my drift). So, what is the solution? Change the design! Instead of having the control valve on the top of the tank, move it to the side of the tank, which we call air injection on steroids when it is coupled with ozone to take the place of air.
Our Aeration Based Iron Removal System
Air-Injection on Steroids – We do not like to apply air injection systemson any water supply with more than six (6) ppm of iron unless we use ozone instead of air. In that case, the iron filter draws in ozone, which is an even better oxidizer than oxygen. Still, we do not recommend using an air injection iron filter on iron levels over ten (10) ppm.
We sell direct and eliminate-the-middlemen, so we can't send out a service tech every time a customer has a problem. I know that some people will write in and say that they have an air-injection iron removal system, and it works, but they never say how much iron they have. That's the essential part.
Pros & Cons:
This is probably the least expensive and best methodology for iron removal, especially if the iron levels are six (6) ppm or below (10 ppm with the optional ozone draw).
The Cons are that you have to be careful if you have IRB (Iron Reducing Bacteria) or SRB (Sulfur Reducing Bacteria).
Ozone is a more potent oxidant than chlorine, but ozonation equipment is typically more expensive to operate because of higher electricity consumption. With ozonation, the raw water is placed in contact with ozone in the initial step of the treatment process. This causes the iron, sulfur, and/or manganese to oxidize and "fall out." Next, the precipitate and excess ozone is filtered and destroyed by a granular activated carbon filter.
For an ozone system to be successful in a humid climate, it must have an "air dryer" because humid air does not make good ozone. Additionally, most ozone generators do not produce enough ozone to properly oxidize the levels of iron, sulfur, and/or manganese. If anything, an ozone generator should be oversized in order to handle high flows or changing water conditions.
Pros & Cons:
Ozone has an extremely high initial cost with a very low operational cost. Over the years, we have replaced many systems because they were undersized and do not have air dryers or oxygen concentrators. Also, you must make sure you "destroy" the ozone or you will develop pinholes in copper pipes. It is a great technology, but it can be four to five-time the cost of other systems.
Continuous Regeneration Greensand Iron Removal Systems
Another common method uses an oxidizing filter media known as "greensand." A bed of greensand is comprised of manganese oxide coated resin pellets or beads which provides both an oxidizing environment and filtering capacity. Oxygen is released from the manganese oxide coating to oxidize the dissolved iron in the raw water passing through the bed. The oxidized iron particles are trapped in the resin bed until removed during the backwash cycle when the manganese oxide coating is regenerated with chlorine or potassium permanganate.
The iron particles must be flushed out during the backwash cycle so that the resin bed does not become clogged. Greensand systems do not require high dissolved oxygen content but work best when the water pH is above 7.5. These systems are popular when a large volume of water is needed and the iron is not over ten to twelve ppm.
Pros & Cons:
It is our opinion that these Greensand systems (which actually use Greensand Plus) are a good choice in high flow applications, including irrigation and agricultural use. Generally, we do not use this for homes. The upfront cost is moderate, but the plugging of the injection point is something that you will have to deal with. It is our opinion that there are better methods for residential applications.
Pyrolox, Filox & Katalox Light Based Iron Removal Systems
All of the media and others that end in "ox" are manufactured using manganese oxide which ss the water flows through the filter tank containing any type of "ox" media, a reaction occurs where the dissolved oxygen and the dissolved ferrous iron compounds form an insoluble ferric hydroxide. It sounds like a great idea… in theory. The problem is that most of these media weigh over 100 pounds per cubic foot. That simply means to backwash it, you have to use a tremendous amount of water for a long time.
There are two problems with this: (1) Many wells do not produce the requisite volume to "lift" the bed in the backwash" cycle, so the iron is never fully backwashed out; and (2) The amount of water these systems run to drain is insane!
Katalox Light is lighter than the other media, weighing in at sixty-six (66) pounds a cubic foot. It works in a pH range of 5.8 to 10 .5 and has a lifespan of 7 to 10 years. While the manufacturer rates their media at a much higher ability to remove iron, we limit it to 15 ppm of iron.
Pros & Cons:
I know that there are many who swear by Filox and Pyrolox, but in my opinion, they are too heavy and wasteful. Things that sound too good to be true usually are. There are many wild claims around the "ox" products. Be careful what you believe. Water is fluid things… no pun intended!
Polyphosphate Sequestering Based Iron Removal Systems
Polyphosphate is injected into a water supply to keep the iron in the solution. Polyphosphates do not remove the iron from water. Instead, they stabilize and disperse the iron so that the water remains clear and does not produce iron stains.
However, polyphosphate treatment may not prevent iron from precipitating when water is boiled and boiling can cause reversion to the orthophosphate which has no equivalent sequestering action. They reduce staining by retaining these metals in solution and preventing oxidation. Most polyphosphates are only effective for levels of iron and manganese less than about 3 ppm and if the water will not be heated. Heating releases the metals and allows oxidation to occur.
Pros & Cons:
Polyphosphates can work on low levels of iron, but they must be continually injected and the levels monitored. In applications requiring the removal of iron, it does not typically shine.
Hydrogen Peroxide Based Iron Removal Systems
This is my opinion and I have saved the best for last. If someone put a gun to my head and said "Install something that works, or I will blow your brains out," I am certain that I would live longer than with any other treatment process. Hydrogen peroxide is forgiving, predictable, and works almost regardless of the levels of iron. You just have to apply it properly.
Hydrogen peroxide or H2O2 is a much better oxidizer than oxygen and it doesn't require that a service technician move in with you. Hydrogen Peroxide works every time and since it is such a great oxidizer, it does not leave all that iron sludge to clean up and there are no injectors to plug. Injecting H2O2 is simple and very low maintenance… and unlike chlorine, the injection point does not plug frequently. It is not uncommon for hydrogen peroxide to work for 5+ years without any maintenance except for adding peroxide.
Hydrogen peroxide is injected just ahead of a catalytic carbon filter. Not only does peroxide not require contact time, contact tanks or pressure tanks just dilute the H2O2 making it less effective. That is why a proportional injection system is the most effective method.
The cost of a system is on the moderate to the high side, but it operates for many years without any maintenance… except for adding the H2O2. An average family will spend $200 to $400 a year on peroxide, but most think that is a small price to pay to have iron-free water. The only drawback to an H2O2 system is the annual peroxide cost.
With over 45 years of water treatment experience, I can tell you that I have tried just about every iron removal method - many times over. I have made every mistake in the world when treating water for iron, which may qualify me as somewhat of an expert, however, you need to understand that exceedingly high levels of iron (10, 15, 29, 30+ ppm) have to be treated on an individual basis.
A one-size-fits-all, off-the-shelf system is probably not the answer. In extreme problem water applications, you should consult a Master Water Specialist for the solution. Remember that the place where you start is with a well-detailed water analysis from an independent lab. Then we can see what levels of contaminants are in your water, as well as other competing contaminants, and engineer a system that will work for you.
Now that you’ve learned a thing or two about iron removal systems, which do you think is the best overall system? Comment below and let us know what other types of water treatment you’d like to learn about.