Does Reverse Osmosis Remove Iron: Top Iron Removal Method

Does Reverse Osmosis Remove Iron from Drinking Water

If you are a homeowner who is looking for ways to remove iron from your drinking water, you may be wondering if reverse osmosis is the best option. In this blog post, we will discuss the benefits of reverse osmosis and whether or not it can effectively remove iron from your water. Keep reading to learn more!

It is not recommended that you run anything more than 0.3 ppm of iron into a reverse osmosis system. Although it will remove iron, this contaminant will plug up the filters very quickly. If you have iron in your water, you should treat those issues at the point of entry or on the whole with a berm or greensand filter.

Reverse osmosis can remove iron from your drinking water, but it can be problematic if you have more than 0.3 parts per million of iron in your water. High concentrations of iron tend to foul the sediment and carbon filters on your RO filter and can plug the membrane. In this case, it is recommended that you treat the iron at the point of entry or use a whole-house filter using alternative iron treatment such as berm, greensand, or Pyrolox filters.

Problems Associated with Iron in Drinking Water

While small amounts of iron in drinking water are not harmful, it does cause problems that make it undesirable.

The EPA classifies iron in well water as a second contaminant, which means it has no harmful effects on health. EPA set the Maximum Contaminant Level for iron at 0.3 milligrams per liter (mg/l). This is only a suggestion, not a federal regulation.

Iron can give water a rusty or metallic taste, and it can also stain fixtures and clothes. While it is not a health hazard, most people don’t want it in their drinking water. There are several ways to remove iron from water, but the most common is through a process called reverse osmosis.

Reverse osmosis is a process that uses pressure to force water through a membrane, which removes most of the contaminants in the water. This includes iron, as well as other metals, minerals, and salts. So, if you’re looking for a way to get rid of that rusty taste or unwanted stains, reverse osmosis is a good option.

Rust stainsIron stains in sink

Water that contains iron can stain plumbing fixtures, clothes, and dishes. In high concentrations, the stains can be problematic, especially in bathroom sinks and other porcelain fixtures. Removing these stains can be very difficult, occasionally resulting in the need to replace the stained fixture.

Taste and odor problems

Iron in drinking water can cause a metallic taste that some people find unpleasant. In addition, water that contains iron may have an unpleasant odor. In high concentrations, it can cause gastrointestinal distress.

Fouled pipes and plumbingIron fouling

High levels of iron in water can cause a buildup of rust in pipes and fittings, which can eventually lead to clogs and pipe damage. In addition to the problems listed above, iron can also cause a buildup of sediment in your water heater, which can lead to decreased efficiency and, in some cases, failure.

Many people have problems with iron-reducing bacteria, which can cause a slime buildup in pipes and fixtures. These bacteria can also release an unpleasant odor.

If you are concerned about iron in your drinking water, the best course of action is to have your water tested by a qualified professional. Once you know the level of iron in your water, you can decide on the best way to remove it.

Key Takeaways
Reverse osmosis can remove iron from drinking water, but it is not recommended for high concentrations of iron (>0.3 ppm).
Iron in drinking water can cause taste and odor problems, staining of fixtures and clothing, fouled pipes, and plumbing.
Iron can be found in well water due to groundwater sources and corroding pipes.
Effective methods for removing iron from water include oxidation, chemical treatment, green sand water filters, and berm water filters.
If you have an RO system and are concerned about iron fouling, you may need to install a pre-filter to remove iron before it reaches the RO membrane.

How Does Iron Get in My Drinking Water

Iron can be found in well water for a few reasons. One reason is that well water is sourced from groundwater, and iron is one of the most common naturally occurring metals in Earth’s geology. If the groundwater has contact with rocks or minerals that contain iron, it readily dissolves this metal where it ends up in your water. Additionally, corroding pipes can also release iron into well water.

Does Reverse Osmosis System Remove Ironreverse osmosis filter under sink

Reverse osmosis water filters remove 99+% of dissolved iron from water. At low concentrations, these systems are a reliable and effective method for removing iron. However, at high concentrations, iron can foul the system, resulting in increased maintenance costs and reduced treatment efficiency.

Effectiveness of RO filter for iron removal

A reverse osmosis filter effectively removes many contaminants such as chlorine, fluoride, lead, mercury, sodium, and nitrates. RO systems can also help remove iron from drinking water.

Testing data indicates that virtually 100% of iron is removed when water passes through RO water filters. At low levels, you can expect your RO system to work well and provide you with clean, iron-free water.

Do you have high levels of iron in your water? If so, fouling becomes problematic, and you should use an alternative treatment method.

Iron fouling

At high concentrations, iron can foul the reverse osmosis membrane, causing a decrease in treatment efficiency. The fouling occurs in several locations, including:

  • sediment filter
  • activated carbon filter
  • RO membrane
  • tubing and interconnecting parts

The sediment filters can quickly become plugged with oxidized iron solids. In addition, the iron may form a scale deposit on the particle filter, resulting in reduced flow and diminished filtration capacity.

The activated carbon filter also collects a lot of iron and can become fouled in a short period of time. This results in reduced chlorine removal which can lead to degradation of the membrane.

The membrane is especially susceptible to iron fouling because the iron deposits and collects in the pores. Once the small pores become plugged, the flow rate through the RO unit drops off and the treatment efficiency of the system declines.

Maintenance concerns

The collection of iron deposits and scale in the sediment filter, activated carbon filter, and RO membrane results in increased maintenance requirements. You may have to replace the filters every month as opposed to the recommended six months. As you can see, the cost to replace the filters so frequently can add up very quickly.

You may also have to clean the RO membrane more frequently. In some cases, you may need to replace it entirely if it becomes too fouled with iron deposits.

Read my article about RO filter maintenance.

How to Remove Iron from Water

Iron can be removed from water using a variety of methods. The most common systems used to remove this metal are summarized in the table below.

Iron Removal MethodDescription
Oxidation with air or chlorine followed by filtrationA process that involves adding air or chlorine to water to oxidize the iron, then filtering it out of the water.
Chemical treatment with a ferricyanide, polyphosphate, or phosphonate compoundA process that involves adding a chemical to water to bind with the iron and remove it from the water.
Green sand water filtersA filtration system that uses a specially processed form of the mineral glauconite to remove iron from water.
Berm water filtersA type of filter that uses a mixture of materials (such as sand and anthracite) to remove iron from water.

The most effective method for removing iron from water depends on the concentration of iron and other contaminants in your water.

If you have low levels of iron, reverse osmosis can be an effective option for iron removal. However, if you have high levels of iron, you may need to use a different method such as chemical treatment or a berm filter.

What If You Have an RO System with Iron

If your house already has a reverse osmosis system, and you are concerned about treating iron, you may need to install a pre-filter that will remove iron before it has a chance to foul the RO membrane. Although it will remove iron and hardness, there are better methods for removing these compounds from your drinking water.


Does reverse osmosis remove iron from well water?

RO systems can help eliminate iron from water. At low concentrations, it is a reliable and effective method for removing iron. However, at high concentrations, iron can foul the system, resulting in increased maintenance costs and reduced treatment efficiency.

Does RO water filters remove manganese?

Reverse osmosis can remove manganese from water. RO also removes iron.

Conclusion About Reverse Osmosis System

Reverse osmosis systems can remove iron from water. However, at high concentrations, it can foul the system and reduce treatment efficiency. If you have high levels of iron in your water, you may need to use a different method such as chemical treatment or a berm filter.

Boch Richard

Richard Boch is a chemical engineer responsible for designing water filtration systems for industrial and residential customers. He has more than 20 years of experience with ion exchange, activated carbon, and reverse osmosis. Richard's expertise has made him a go-to source for municipalities and businesses looking to improve their water quality. When he's not working, Richard enjoys spending time with his wife and two young children.

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