Iron is an essential mineral for human health. Its deficiency is one of the leading causes of anemia worldwide, so it’s important to make sure you get enough iron in your diet. (1)
However, when it comes to drinking water, too much iron can be a problem. This is especially true for households that rely on well water.
If your well water is leaving a bad taste in your mouth, you need to know what the safe limits are for iron and how to remove it from your drinking water.
What is Iron?
Iron is a chemical element symbolized as Fe. It’s the most abundant element on earth by mass and is used in metal production for a variety of purposes, such as building bridges and making bicycle chains. In smaller doses, iron is necessary for the production of hemoglobin, a key component of red blood cells.
Iron is prevalent in the earth's inner and outer core, making up about 80% of both. It can also be found in our blood and is a common material for construction and engineering. As it’s so widespread, it’s not surprising that iron can also end up in our water supply.
When it comes to drinking water, iron is present in three forms: ferric iron, ferrous iron, and iron bacteria.
Ferric Iron (Fe3+)
Ferric iron (Fe3+) is the most common contaminant form of iron. It’s also known as red-water iron, is insoluble and appears as sediment in the water, giving it a reddish-brown color.
Ferrous Iron (Fe2+)
If the iron in your well water has had limited exposure to oxygen, it will be in the form of ferrous iron. It’s also known as clear-water iron, is soluble and initially not visible, but if left in a glass, it will turn rust-colored over time due to oxidization. It can also stain your toilet bowls and sinks around the house.
Iron bacteria are less common than ferric and ferrous ones but can also contaminate water. These small organisms use dissolved iron as an energy source. While they are not harmful to humans, they can produce an orange-brown slime and an oily sheen in the water, as well as a foul odor and unpleasant taste. (2)
How Does Iron Get Into Well Water?
There are several ways that iron can get into well water. One way is through the dissolution of iron present in soil by rainwater or snow melt as it seeps through the earth. Corroding steel pipes can also contribute to iron in drinking water, and natural deposits of iron can leach into the water supply.
Shallow wells are more likely to have organic iron in the form of ferric iron. This is because the water in shallow wells has been exposed to oxygen, causing the iron content to oxidize and form sediment. (3)
Ferrous iron, on the other hand, is more commonly found in deep wells. In these wells, the water has had less exposure to sunlight, so the iron has not had a chance to oxidize.
It’s unlikely that iron bacteria will be present in your well naturally. These bacteria are usually introduced through improper servicing or the use of unsanitized materials.
Is Iron Dangerous in Drinking Water?
Iron levels in drinking water are unlikely to pose any health risk. Iron is toxic in concentrations of 20 mg/kg, but it’s unlikely to exceed 10 mg/L in well water. (4, 5)
The Environmental Protection Agency (EPA) lists iron as a secondary contaminant, meaning that the limit of 0.3 mg/L is a non-enforceable guideline. Despite this, the EPA sets the limit for iron in water at 0.3 mg/L. Above this level, the iron content becomes objectionable and impacts the taste, odor, and appearance of your drinking water. (6)
The World Health Organization (WHO) found that the median iron content in rivers is 0.7 mg/L. This suggests that it’s highly likely that the iron content of your well water is too high. (7)
What Are The Benefits of Iron in Drinking Water?
Iron is an essential mineral for maintaining good health. It helps to meet the body's dietary requirements for iron and prevent anemia, a condition in which the body doesn’t have enough red blood cells. In addition, iron plays a vital role in transporting oxygen in the blood.
According to the Environmental Protection Agency (EPA), a concentration of 0.3 mg/L of iron in drinking water can contribute approximately 0.6 mg/day to your diet. This represents about 7% of the recommended daily intake of iron for men and 4% for women aged 18 to 50. (8, 9)
A healthy intake of iron has the following benefits:
- Prevents anemia by increasing red blood cell production
- Helps with cell growth and development
- Regulates body temperature
- Boosts the immune system (10)
What Are The Harmful Effects of Iron in Drinking Water?
Too much Iron in drinking water can affect its taste and appearance, giving it a metallic taste and reddish-brown color. Iron overdose can lead to nausea, diarrhea, and liver damage. In rare cases, it can also cause hemochromatosis. (11, 12)
It’s unlikely that toxic concentrations of iron will be found in drinking water, as iron poisoning is typically caused by overdosing on iron supplements rather than any natural source. (13)
Impact of Iron on Drinking Water: Taste, Smell, and Appearance
The main concern of excess iron in your well water is the negative impact on the taste, smell, and appearance of your drinking water.
High concentrations of ferric iron can give your water a red or brown tinge and a metallic or even bloody taste, as well as an unpleasant odor.
Ferrous iron can also cause your water to taste and smell bad, but it doesn’t discolor the water as it comes out of the tap. Instead, ferrous iron-contaminated water only discolors once it has been left to stand.
Effects of Iron on Skin and Hair
According to one study conducted in India, higher levels of iron in groundwater can damage hair and nails. Iron will build up in hair and nails if you’re consistently exposed to a higher concentration in your drinking water. (14)
How Does Iron in Water Damage Your Home?
The high iron content in your water supply can clog pipes and cause sediment and sludge to build up. This can damage appliances and cause stains on toilets, sinks, and bath fixtures.
Brown and orange stains around kitchen and bathroom fixtures are a hallmark of high iron content. While these stains can be removed with a commercial stain remover, damage to pipes and appliances may be harder to spot.
How to Detect Iron in Drinking Water
If your drinking water has a metallic taste or appears reddish-brown, it may have a high iron content. When iron concentration is high, you’ll likely be able to taste and see it right away. However, water that is contaminated with ferrous iron may be clear when it comes out of the tap but will turn reddish brown if left standing on your countertop.
How to Test for Iron in Water?
There are a couple of options for testing the iron levels in your drinking water. You can either perform a home iron water test or request a professional test from local water quality experts. Environmental departments or county governments often have lists of licensed laboratories in your area that can test your water.
While home water tests are usually cheaper and provide immediate results, they only identify a narrower spectrum of contaminants. If you’re only concerned about iron, this may be sufficient. However, the Centers for Disease Control and Prevention (CDC) recommend testing your well at least once a year for coliform bacteria, lead, and total dissolved solids. (15)
How to Remove Iron from Well Water
Ferric iron can be removed from well water using a sediment filter. To remove ferrous iron, you will need to use a different method such as aeration, chemical injection, or catalytic media to oxidize it. After it has been oxidized, it can then be filtered out using a sediment filter.
Water softeners specifically designed for well water can also be effective at removing small concentrations of ferrous iron. Some whole-house water filters combine filtration and softening technology, making them effective at removing both types of iron.
The Best Water Filters for Removing Iron from Drinking Water
Different types of iron require different water filtration methods. Here are the best options for removing iron from well water:
Because ferric iron is in a precipitate form, it can be filtered by sub-micron sediment filters with a fine mesh that allows water to pass through while trapping iron particles. To effectively remove ferric iron from your drinking water, you will need a sediment filter with the right micron rating.
For removing ferrous iron, a combination of an oxidizing media and a sediment filter is typically the most effective approach. When ferrous iron comes into contact with an oxidizing media, it’s oxidized into ferric iron, which can then be captured by a sediment filter. Here are a few options for oxidizing media:
Manganese greensand is a popular choice that can handle iron concentrations of up to 15 ppm. If you’ve ferrous iron in your well water, you might want to consider the SpringWell Whole House Filter System, which uses a combination of greensand filter media and air injection to effectively filter out even the highest levels of iron.
Birm is another popular oxidizing media that can be used to extract dissolved iron from well water. Unlike manganese greensand, birm doesn’t require the addition of a chemical oxidizing agent, but it’s only effective at high pH levels.
Air injection filters can also be used to oxidize ferrous iron into a precipitate form, allowing sediment filters to remove it. Air injection is often used in combination with an additional oxidizing media to complete the process of precipitating the iron.
Water softeners for well water can remove iron, but they may quickly become clogged or damaged if the iron content is too high. Therefore, they are not usually recommended as the sole method of iron removal. Iron, like calcium and magnesium, is a positively charged cation. Water softeners that use ion exchange and salt to replace these minerals with sodium can remove ferrous iron in concentrations of 2-5 mg/L, but may not be effective at higher levels. (16)
Kinetic Degradation Fluxion (KDF)
KDF is a popular filtration method that uses a chemical process called redox (oxidation/reduction) to remove heavy metals, including iron, from water. It’s made of high-purity granular copper-zinc and works by converting ferrous iron into its ferric form. Once the iron has been converted, a low-micron sediment filter can be used to remove it from the water. KDF is effective at removing chlorine as well.
Removing Bacterial Iron
Bacterial iron can be challenging to remove once it contaminates your well water. The most effective method for eliminating this type of iron is shock chlorination. This involves introducing a high concentration of chlorine (around 200 ppm) to your water supply.
To effectively disinfect your well, pipes, and pumps, the chlorination process must reach all depths. It will kill the bacteria and make it possible to remove any remaining iron using other methods.
Although the iron content in your drinking water is not likely to pose a health threat, it can still cause unsightly stains in your sink and toilet. Plus, who wants to be reminded of the time they bit their tongue when they go for a refreshing glass of water?
Removing iron from your water supply can improve both its taste and odor, as well as protect your plumbing and appliances. The most effective well water filtration systems use a combination of oxidizing media and sub-micron filtration to remove both ferric and ferrous iron from your drinking water.
Overall, taking the steps to remove iron from your well water is worth the effort.