Why Micron Rating Matters in Water Filtration

When shopping for a whole-house water filter system, there are a few things you need to consider to make an informed purchase. Of course, you want an affordable system that can filter large volumes of water. However, there’s something else just as crucial to keep in mind:  the micron rating.

Whole-house filtration typically involves a multi-stage process with various micron-rated filter cartridges. The micron rating indicates the filter’s ability to remove contaminants based on size. Generally, filters with a lower micron rating provide better protection against harmful pollutants like bacteria, sediment, and heavy metals. In contrast, higher-rated filters may let some of these contaminants slip through.

So, the question is, what’s the ideal micron rating for each filter cartridge in your whole-house system? It can be daunting to figure out, but don’t worry—we’ve got you covered. This comprehensive guide will help you understand everything you need to know about water filter micron ratings, including what they are, why they matter in whole-house filtration, and selecting the perfect micron rating for your whole-home filter system.

What is a Micron?

To understand what a micron rating is, we must first define a micron. A micron (μm) is a measurement unit representing one micrometer or one-millionth of a meter. It’s often used to describe the size of water contaminants.

If you’re wondering just how small a micron is, consider that one micron equals 0.00004 inches or 0.0001 cm. Remember that the average cross-section of a human hair is around 70 μm, and a red blood cell has a diameter of about 7 microns. So, you can imagine how tiny a micron is. And, so you know, we can only see particles larger than 40 μm with our naked eye. Anything smaller than that requires a microscope.

What is a Water Filter Micron Rating?

A water filter’s micron rating refers to the size of the gaps between the filter media components, which controls the size of the contaminants that can pass through the filter. For example, if your water has dirt particles measuring 5 µm and your whole-house system’s sediment filter has a micron rating of 5 µm, it can effectively filter out those sediments and anything larger than 5 µm. But if the sediment filter has a micron rating greater than 5 µm, these pesky particles will slip through the filter and enter your home, potentially causing damage and health hazards.

Types of Contaminants Water Filters with Different Micron Ratings Remove

Filters with different micron ratings are equipped to eliminate various contaminants depending on the size of the particles.


From E. coli bacteria to salmonella virus, tap water can be a haven for various pathogens—many of which you never want in your drinking glass or shower water. Removing these nasty microbes requires a fine filter due to their smaller size. Filters rated between 0.5 and 1 micron can do the trick since their pore sizes are small enough to trap microscopic organisms linked to a broad range of dangerous diseases.

Related: Best Water Filtration System to Remove Bacteria & Viruses from Water


Like pathogens, sediments like dirt, rust, and sand are no strangers to tap water. Not only can they clog and damage pipes and appliances, but they can also affect how your water looks, tastes, and smells and cause severe health issues if ingested over time. Experts recommend filters with a micron rating of 1 μm or less to prevent these unwanted elements from entering your drinking water. Filters with a 0.5 μm or lower rating can remove sediments, including clay and silt, that may pass through standard filters.

Related: 7 Signs of Sediment Buildup in Your Water Heater


Toxic chemicals like chlorine and PFAS can also contaminate tap water, sometimes due to industrial runoff, disinfection, leaching from old plumbing systems, etc. If you are concerned about chemicals getting into your water supply or want to remove them, an ultra-fine filter with a micron rating down to 0.5 microns is your best bet. This type of filter can trap chemical contaminants in tap water and prevent them from escaping into your home’s drinking water supply.

Related: Chlorine in Drinking Water: The Good, the Bad, and the Ugly

Common Water Filter Micron Sizes and What They Filter Out


Also known as ultra-fine filters, 0.5-micron filters can eliminate most bacteria, cysts, protozoa, and other contaminants down to 0.5 microns in size. They can also eradicate larger ones, such as Giardia lamblia and Cryptosporidium, linked to human gastrointestinal illnesses. But that’s not all. Filters with such a low micron rating can eliminate particulates and reduce chlorine, organic chemicals, lead, and other heavy metals.


1-micron filters can remove many bacteria and parasites, including E. coli, Salmonella typhimurium, Shigella dysenteriae, and some viruses like the Hepatitis A virus (HAV). The pore structure of these filters helps provide adequate protection against harmful contaminants in many public drinking water sources.

5 microns

Best suited for sediment removal, 5-micron filters are ideal for whole-house filtration systems where large volumes of water need to be filtered quickly without compromising performance. They also offer some protection against larger organisms like Giardia lamblia and cysts but not against smaller pathogens, such as E. coli. Therefore, you shouldn’t rely solely on 5-micron filters to combat bacterial contamination.

10 microns

10-micron filters may remove certain invisible particles from water, but not bacteria or viruses. However, 10 microns is still tiny and can benefit many industries, from oil to chemical facilities, because they have a longer filter life and slightly better flow rates. But like the filters with lower micron ratings, 10-micron filters are also susceptible to clogging.

Why Micron Ratings are Vital for Whole-House Filtration

Whole-house filters typically use a multi-stage process to eliminate contaminants of various micron sizes, including sediment, heavy metals, and sometimes bacteria. For instance, when water enters our Whole-House Water Filters, it undergoes a meticulous filtration process that involves the following steps:

  1. Initially, the water flows through a KDF bed containing copper-zinc alloy media. This innovative technology helps reduce chlorine, chloramines, and even heavy metals that dissolve in water, like lead.
  2. From there, the water moves to a powerful 0.5-micron activated carbon filter, which uses catalytic coconut carbon to eliminate contaminants, including PFOS, PFAS, herbicides, pesticides, and other chemical compounds. The carbon filter also helps improve the water’s taste, odor, and smell while eliminating harmful organic compounds.
  3. Finally, the water passes through a 5-micron sediment filter that acts as a polishing agent to capture any sand, silt, clay, or other tiny particles still in the water.

Micron ratings are crucial to virtually every stage of the whole-house filtration process. Without knowing the size of different particles in water, water filter manufacturers wouldn’t know how to properly eliminate particles that can’t be seen without a microscope.

How Many Microns Should Your Water Filter Cartridge(s) Be?

There’s no one-size-fits-all when it comes to water filter micron ratings. As explained earlier, different water filter cartridges have varying micron ratings that cater to specific filtration needs. Some cartridges work better at removing tiny elements, such as bacteria, while others are more effective at filtering out larger particles, like dirt and sand. So, if you’re trying to determine the ideal micron rating for your water filter, there are a few things you need to consider:

Where do I live?

Well and city water quality can differ significantly from region to region. For instance, if you live in an area where the dirt is super fine, like New York, you may need a filter with a micron rating of 1 or smaller to capture all the particulates.

Well water is likely to contain bacteria, sediment, and heavy metals, which require a sediment filter, carbon filter, and a UV Water Purification System in a whole-house setup. At the same time, city water often contains chlorine or chloramines and various well water contaminants, necessitating a similar system.

Related: Is Florida’s Tap Water Safe to Drink? | What’s Causing California’s Drinking Water Crisis?

What do I need to filter out?

Secondly, you must identify the impurities you want to remove from your water. You may already know the contaminants you want to filter out. If not, using an at-home test kit or arranging a laboratory water test will provide the necessary information. Knowing the size of the impurities will help you choose the right filter with pores of the correct size. For example, if you want to remove tiny bacteria, a 5-micron sediment filter media won’t suffice; you need a filter with a micron rating of 1 or lower.

Related: 10 Common Problems a Water Test Can Detect in Tap Water

What’s my required level of filtration?

It’s also essential to think about your required level of filtration. While the micron rating can give you an idea of a filter’s effectiveness at achieving solid/liquid separation, it’s not the only factor to consider.

Filters can be constructed from different materials, flexing and changing according to various operating conditions. Therefore, the pore’s shape can change, and particles larger than the micron rating can occasionally pass through. This is why micron filters are often categorized into two main types: absolute and nominal.

Absolute filters will trap 99.9% of the particles larger than a specified micron rating, while nominal filters indicate the approximate size particle, most of which will not pass through the filter. Typically, nominal filters retain 85% of the particles of the size equal to the nominal filter rating.

Benefits of Low-Micron Filters

Many shoppers rarely consider the micron rating for the specific filters when in the market for a whole-house system—a big mistake if you ask us. However, purchasing a system with low-micron-rated filter cartridges provides several incredible benefits for your health and household.

Improved Taste and Odor

If you want to improve the taste and odor of your drinking water, consider investing in a high-quality whole-house system with low-micron filters. These filters work wonders by removing small particles like dirt, sediment, rust, chlorine, and other impurities that can make your tap water taste or smell unpleasant. Not only that, but such a system also helps reduce the levels of heavy metals like lead that can sometimes be present in municipal water supplies. Consuming these metals over time could have serious health consequences.

Related: Common Odors in Tap Water and How to Remove Them

Better Protection from Harmful Contaminants

Another reason to use a low-micron-rated water filter is the increased protection it provides against harmful contaminants like bacteria and viruses that could be lurking in your drinking water supply. These filters are designed to capture even the tiniest particles, which means they’re much more effective at protecting you from harmful contaminants than standard filters. With one of these filters, you can rest easy knowing that you’re drinking clean, great-tasting water straight from your tap without worrying about any harmful contaminants sneaking in.

Drawbacks of Low-Micron Filters

While it’s true that a smaller micron rating can remove more contaminants from your water, you should be aware of some potential drawbacks to using low-micron filters.

Flow loss rate/decreased water pressure

One of the main concerns with low-micron filters is flow rate loss. As the filter’s micron rating decreases, the filter becomes more efficient at removing particles but restricts the water flow. This can be a problem if you have a low-flow well pump or if you’re using a filter with a minimal micron rating. To avoid flow rate loss, consider using a larger pump or a filter with a higher micron rating.

Frequent filter replacements due to clogging

Another issue is that filters can become dirty over time, especially using a filter with a small micron rating. As the filter removes particles from the water, those particles accumulate in the filter. Depending on the quality of the water going through the filter, it may need to be replaced more frequently if it has a small micron rating. This can increase the filter’s cost and require more maintenance.

Final Thoughts

Choosing a low-micron water filter can significantly benefit your home’s water quality. By capturing smaller particles and contaminants, these filters can provide a higher level of purification and ensure that your water is safe and healthy to use. However, remember that filters with lower micron levels may be more expensive than those with higher ratings. This is because they require more advanced technology and materials to remove smaller particles from the water effectively. Additionally, filters with low micron levels may require more frequent replacement or maintenance due to their increased effectiveness in capturing contaminants.

If you’re interested in a whole-house water filter with a low micron rating, we recommend choosing a reputable brand that uses high-quality materials and advanced filtration technology. This can ensure you get the best possible performance from your filter and that your water is purified to the highest standards.

If you have any questions about selecting a filter with the right micron level for your home or want to learn more about our revolutionary whole-house water filters, don’t hesitate to contact us. Our team of friendly experts can help you choose the right filter for your needs and ensure that you get the best possible water quality in your home.