Why won’t my cartridge filter work on iron?
The vast majority of water filtration systems found in homes across the US contain a type of filter media called granular activated carbon (GAC).
If you currently own a water filter system, it probably uses granular activated carbon.
While these filters cover a wide range of contaminants and greatly improve the taste and smell of drinking water, there are certain things they can’t do.
Simply put, common GAC filters are not designed to capture iron.
Undissolved iron particles quickly clog up GAC filters, while dissolved iron passes straight through them.
This is because GAC filters don’t oxidize contaminants. Oxidization is the process used to turn dissolved metals like iron into an insoluble form that can be removed by a filtration media.
Without an oxidizing stage, no water filter can remove iron in any significant amount.
What about my sediment cartridge filter?
Another type of cartridge filter that people commonly use when trying to tackle iron contamination is a micron filter or sediment filter.
By passing water through fine mesh screens, these devices filter out tiny particles of iron or rust from the water supply.
If you’re currently using a sediment filter to address your iron issues, you’ve probably noticed the replaceable filter screen quickly turning orange or brown as it captures contaminants.
Undissolved iron collecting on a sediment filter cartridge
Sediment filters can do a good job of removing undissolved iron from the water supply. However, when used without an oxidization stage, they can’t remove dissolved iron.
As this dissolved iron moves through your plumbing system, it still creates contamination issues.
So, while sediment filters are useful for removing undissolved iron particles, they’re not very effective when used alone.
If you’re certain that undissolved iron is the only major type of iron contamination in your well, we recommend the Culligan WH-HD200 for small particulate matter.
It’s one of the most well-reviewed sediment filters online, and is compatible with a range of different micron screens, meaning that you can target specific contaminants.
What about my KDF (Kinetic Degradation Fluxion) cartridge filter?
KDF filters are a less common, but still popular, type of home cartridge water filter. They work by using a combination of metals like copper and zinc, which act as a catalyst in water.
Because KDF filters do oxidize contaminants, they are able to remove both dissolved and undissolved iron from well water.
However, their performance and lifespan are normally much lower than injection filter systems.
If you choose a KDF cartridge filter that’s not rated to handle the levels of iron in your well water, then you’ll be left with some iron content in your water post-filtration.
This might not be an issue from a water quality standpoint, but even low levels of iron in water can lead to iron bacteria growth.
If your well water contains low levels of iron and you’re looking for an inexpensive cartridge filter to fix the issue, we recommend this 3-stage KDF system from APEC Water.
As the winner of our “Best under $500” category in our 2022 Best Well Water Filtration Systems review, we think the APEC filter offers a decent compromise of price and filtering power.