Do water softeners remove iron from well water?


One confusing topic that well owners often raise is whether a water softener can also function as an iron filter.

It’s true that salt-based water softeners do have some ability to remove iron, but the details of how and when you should consider a softener system for iron-contaminated well water can get a little tricky.

Let’s go through the facts on using a water softener to remove iron from well water.

Water softeners are designed to capture calcium and other hard minerals – but can they also remove metal elements likes iron?

Key takeaways

  • Traditional ion-exchange water softeners for well water can remove low levels of dissolved (ferrous) iron from well water, up to approximately 2 PPM.
  • However, undissolved (ferric) iron in the water supply can damage softener systems, so it needs to be removed with a sediment filter before the water reaches the softener.
  • Water softeners are generally only effective at removing iron from hard water. Using a softener to remove iron from soft, mineral-free water may not have significant results.
  • Dedicated iron filters for well water are more effective at removing iron, are available at various price points, and can be paired with a softener system.

How do water softeners for well water work?

Water softening systems are designed to remove hard mineral ions that have become dissolved into water as it passes through porous bedrock. Magnesium and calcium are the two most common hard minerals found in US well water.

To remove these hard minerals, most softeners an ion exchange process, where a resin bed coated with a pure salt brine is used to attract and capture mineral ions.

Ion-exchange water softeners work by harnessing the naturally attractive cationic charges of magnesium and calcium, which exchange places with sodium or potassium salt ions and leave the water supply.

Ion exchange vs mineral crystalization

Ion-exchange isn’t the only softening technology available. Instead of exchanging hard minerals with soft salts, some water softeners use a specially designed catalyzation surface to change the format of hard minerals.

These catalyst points cause hard minerals to crystalize, which makes it much more difficult for them to bind to surfaces and form scale.

When shopping for a well water softener system, it’s important to weigh up the pros and cons of different softening technologies to find out which type of water softener meets your filtering needs.

Does a water softener remove iron from well water?

Like calcium and magnesium, iron has a cationic charge. As a result, water softeners that use ion-exchange technology can attract and remove some dissolved iron from well water.

Because it only takes very small amounts of iron to cause discoloration, metallic tastes, or appliance staining, a softener may therefore help to fix iron issues in homes with mild well contamination.

However, the design of ion-exchange softeners and the salt solutions they use mean that most water softeners will not remove iron concentrations over 2 PPM.

The ability of softeners to remove iron is also dependent upon water hardness. In fact, due to the nature of the ionic reactions that occur inside a softener resin bed, softener systems are only likely to work for iron contamination if the well water is hard.

Water softeners do not remove all types of iron contamination

However, no water softener will remove undissolved iron. Undissolved or ferric iron is insoluble, meaning that it’s carried along inside the water supply without being chemically bonded to water molecules. As a result, undissolved iron won’t be attracted to the salt in the softener resin bed.

Water softeners also do not remove or protect against the growth of iron bacteria. Iron-rich water can be a breeding ground for classes of bacteria that metabolize iron, resulting in water stagnation.

To find out how to set up a comprehensive iron removal system, read our explainer article: How to remove iron from well water.

What are the downsides of using a water softener to remove iron from well water?

  • It won’t remove much iron

The iron filtering power of any ion exchange system is limited and will quickly degrade if exposed to well water with serious iron contamination. Most experts recommend filtration systems with air injection or KDF technology for efficient iron removal.

  • Softener resin beds can be damaged when exposed to iron

When iron is removed from water using a softener, it’s left in the resin bed. This can create the conditions for rust formation and corrosion, meaning you may need to use specialist iron cleaning solutions to maintain the softener or even to replace the entire resin bed.

  • You may need specialist salt

People who do choose to use water softeners for their iron contamination issue often need to fill the system with a different, more expensive salt formulation that’s designed specifically for iron-rich water. These salts, which are often referred to as “Iron Out” salt, can improve a softener’s ability to remove iron.

  • It may promote iron bacteria growth.

While a softener may reduce iron levels in well water, it’s unlikely to eliminate them completely. When iron-contaminated water circulates in plumbing systems, it can lead to iron bacteria growth, which compromises water safety. A chlorine injection filter or periodic shock chlorination are the preferred methods of dealing with this type of iron contamination.


Summary: should I use a water softener for my iron-rich well water?

Iron is the second most common problem for well-water users after hard water, so it’s natural to wonder whether a single system can handle both types of contamination.

Standard ion-exchange water softening systems will remove small amounts of iron from hard water, but they are not designed to treat high iron levels. They may also be damaged by undissolved iron if a sediment filter isn’t installed alongside them.

For well water with high iron levels, or softer water that contains iron, an oxidizing filter is the most appropriate filtration method. Check out our reviews of the best iron filters for well water here.