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Iron Filters: The Complete Guide

If you’re on well water, the chances are high you have iron in your water. We get a lot of questions about the effects of iron in drinking water, whether it’s harmful, and how to remove it effectively. If you want the broader system-level view of where iron treatment fits in, start with our complete guide to well water filtration systems.

This guide is going to go through:



The types of iron that can be found in drinking water

Most people know they have iron in their water because of the rusty look of ferric iron. But if you’re on well water you probably have soluble ferrous iron, even if your water looks clear.


Iron that’s dissolved into your water is called ferrous iron. It’s clear and colorless, but can still cause complications with your plumbing and stain your appliances.


Ferric iron on the other hand is a reddish-brown color when it’s coming from the faucet. It’s the oxidized form of ferrous iron. And the reason it stains everything is because it’s actually rusted ferrous iron.


Colloidal and organic iron are different forms of ferrous iron that have been combined with different molecules in your water.

Removing all four types of iron from your drinking water is important. The Environmental Protection Agency (EPA) guidelines for iron in drinking water are 0.3 mg/l. But well water can contain up to 10 mg/l of iron, which could impact your home and water quality.


And because it doesn’t usually cause direct harm to your health at typical household levels, it’s considered a secondary contaminant. But over time, too much iron can still become a problem.


What are the health effects of too much iron?

Besides the plumbing issues that can come up from having iron in your drinking water, there are health issues that you need to be aware of. The long term effects of too much iron can include iron overload in certain situations.


Two questions that are regularly asked: Can iron in drinking water be harmful? And what are the effects of iron in drinking water?


Pregnant women and children need to be especially careful about getting too much iron. They’re more likely to have health issues when there’s excess iron in their drinking water.


And for everyone else, iron can sometimes make your stomach upset.

The bottom line is that too much iron in your drinking water is not ideal. Even though our bodies need it to function properly, too much iron is not good for us.


Iron in your water can also lead to plumbing issues

Too much iron can build up in your pipes and cause clogging. When that happens, you’ll have lower water pressure and slower draining.


Too much iron in drinking water can also give it a metallic taste. A bad taste isn’t always a major health concern, but it can make food and drinks less enjoyable.


Water with excess minerals can also be harder on your skin, fixtures, and plumbing over time. Iron is one of the common well water issues that can quietly affect more than just staining.


How does iron get in your drinking water?

There are two different ways iron gets in your drinking water: seepage and corrosion.


Seepage happens when water from rain and melted snow travels from the ground through the soil to become part of the water supply. If the ground or soil contains iron, it can dissolve into the water while it’s traveling through the ground.


As far as corrosion goes, the combination of water and oxygen causes iron to deteriorate. If the casings and pipes contain iron, the combination of water and oxygen can make them deteriorate. Rust flakes off the well or piping into the water traveling from the well to your tap.


So what should the iron levels in drinking water be?

Iron is measured in parts per million in water. Ideally, you want to reduce the iron in your water to 0 parts per million. Even at 0.3 parts per million, iron starts to stain. We’ve successfully treated iron levels as high as 40 parts per million.


How do you know if you need an iron filter?

A couple of ways you’d know if you need an iron filter are orange or rust-like staining in your toilets, washing machine, and dishwasher. Another is the metallic taste iron can create when you’re drinking it.


If you have ferrous (clear) iron in your water, you may be able to remove lower levels of it with a water softener. But if you have reddish-looking water, you likely have ferric iron that needs to be removed with an iron filter.


How to remove iron from drinking water?

If you have iron in your water, the first thing you need to do is check the pH level of your water. That’s important because a lot of the media used to treat iron need your water to be near neutral pH to work effectively. If you don’t bring the pH of your water closer to neutral, your plumbing and water-using appliances can start corroding because of acidic water.


Iron levels of 1 to 5 parts per million can sometimes be treated with a water softener. If you have higher iron levels than that, you’ll usually need an iron filter. But first, make sure you test your water. You can get water testing kits from Amazon, Lowe’s, or Home Depot.


To remove iron from your drinking water, more than likely you’ll need an iron filter in combination with another piece of water treatment equipment. In many homes, iron is just one part of the overall treatment setup, which is why we recommend reviewing the full well water filtration system guide if you’re dealing with multiple issues at once.


How do iron filters work?

Iron filters work similarly to acid neutralizers. The unit contains a media bed, like a water softener or acid neutralizer. In this case, the filter media doesn’t contain resin, but instead uses an oxidizing agent like manganese dioxide.


When water passes through the bed, the media attracts soluble ferrous iron and converts it to an insoluble state. The oxidizing agent makes the iron and other contaminants in the water larger, making them easier to remove. A filter then captures the iron, leaving your water iron-free.


The iron filter is maintained by periodic backwashing to remove the precipitated iron. Regeneration needs to happen to refresh the oxidizing ability of the media bed, but much less frequently than backwashing.


What’s the best type of filter for removing iron from drinking water?

A Katalox filtration system is able to remove both forms of iron, manganese, and hydrogen sulfide present in well water.


Relatively high concentrations of inorganic iron, whether ferrous or ferric (dissolved or precipitated), may be removed with iron filters. They are similar in appearance and size to conventional water softeners but contain beds of media that have mild oxidizing power. As the iron-bearing water is passed through the bed, any soluble ferrous iron is converted to the insoluble ferric state and then filtered from the water. Any previously precipitated iron is removed by simple mechanical filtration.


Different filter media may be used in these iron filters, including manganese greensand, Birm, MTM, multimedia, sand, and other synthetic materials. In most cases, the higher oxides of manganese produce the desired oxidizing action.


Choosing the right iron filter for you

If you’re comparing options, see our full breakdown of whole house iron filters for well water (what actually works).


Iron levels of 5 parts per million or higher usually require specific iron filters designed specifically for iron removal.

When choosing an iron filter, there are three things you need to pay attention to:


  1. The GPM flow rate of your well
  2. The iron content of your water
  3. The pH of your water


In general, most iron filters require your water to have a neutral pH of around 7. If the pH of your water is too low or too high, it’s harder for the iron filter to remove iron effectively and keep the system performing properly.


The iron filter we recommend most often is the Fleck 2.5 Cubic Foot 2510AIO Iron Filter/Katalox Light. But every situation is different, which is why we have on-staff support that can help. If you have questions or concerns, reach out to us at 800-460-5810, or email us at support@midatlanticwater.net.


If iron is only one of several well water problems you’re dealing with, the best next step is to read our complete guide to well water filtration systems, which shows how iron filters fit into the correct whole-house treatment sequence.


To Recap

Here are a couple of the questions we answered in this complete iron filter guide:



For the broader picture beyond iron alone, read the complete well water filtration guide.