Do Water Filters Remove Bacteria? Find Out Here!

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Wondering whether you can rely on a home water filter to remove bacteria and make your tap water safe to drink? We’ve answered the question, “Do water filters remove bacteria?” in this quick guide.

📌 Key Takeaways:

  • Some water filters remove bacteria, and some water filters don’t.
  • The water filters that can usually remove bacteria are reverse osmosis and ultrafiltration membranes, water distillers, ceramic filters, charged nanofiber filters, and UV purifiers.
  • Carbon filters, KDF filters, ion exchange filters, and other filter media with pores larger than 1-2 microns are usually incapable of removing bacteria from tap water.

⚗️ Does a Water Filter Remove Bacteria?

Yes, a water filter can remove bacteria from drinking water – but not all filters can reduce bacteria or any other waterborne pathogens.

A filter’s bacteria reduction abilities depend largely on its pore size and filtration process.


🧫 How Do Water Filters Remove Bacteria?

Bacteria is a tiny contaminant – usually about 1-2 microns in diameter. That means that it can usually only be trapped by filters that have a pore size that’s smaller than 1-2 microns, making it capable of blocking bacteria from passing through.

When water flows through a filter of this kind, the water particles are small enough to flow through the pores, while the bacteria becomes trapped in the filter media.

✅ Which Water Filters Remove Bacteria?

The water filters that CAN remove bacteria from a drinking water supply are:

Reverse Osmosis Systems

Reverse osmosis water filtration systems use a semi-permeable membrane with a 0.0001-micron pore size that’s small enough to trap bacteria, including coliform bacteria and E-Coli bacteria.

How reverse osmosis filtration works


Ultrafiltration provides a similar filtration process to RO using membrane separation (with a 0.002-0.005-micron pore size) to reduce most disease-causing microorganisms, including bacteria.

Water Distillers

Distilled water is completely pure and entirely free from bacteria. During water distillation, water is heated to boiling point, causing it to evaporate, which kills bacteria and other pathogens.

Ceramic Filters

Ceramic filters with a pore size smaller than 1-2 microns are capable of trapping bacteria and other sub-micron particles as they filter water through their media.

Ceramic water filtration diagram

Nanofiber Filters

Nanofiber filters typically have a pore size of 2 microns or less, so they’re also capable of trapping bacteria in their media.

UV Purifiers

A UV system uses UV purification to alter the DNA of bacteria and other microorganisms, preventing them from replicating and making water safe to drink.

⛔️ Which Water Filters Don’t Remove Bacteria?

The water filters that CAN’T remove bacteria from tap water are:

Activated Carbon Filters

Activated carbon filters of any kind are usually incapable of reducing or killing bacteria in water. Why? Because activated carbon filter pores are usually about 5 microns, which means bacteria can slip through. Carbon filtration is ideal for improving water taste by reducing chemicals and organic contaminants – but not bacteria.

Activated carbon filters: how they work

Most KDF Filters

Most KDF filters are combined with carbon filters to reduce chlorine and heavy metals. Only one type of KDF filter cartridge – KDF 85 – can sometimes remove or reduce bacteria in water, although its main purpose is sulfur and iron reduction.

Ion Exchange Filters

Ion exchange resin is another filter media that’s often combined with carbon media, especially in a pitcher filter. Unfortunately, this filter’s concept of exchanging ions is only really suitable for metals and minerals, not microorganisms like bacteria.

📖 How to Know If a Water Filter Can Remove Bacteria

A good way to know whether a water filter can reduce or kill bacteria is to look for third-party test results. The manufacturer should share these results online. If they don’t, email customer service and ask to see them.

Online testing data should tell you exactly what a filter has been tested to remove, and to what percentage.

An even better way to be certain of a filter’s bacteria reduction abilities is to check for official NSF certifications.

Different systems may obtain different certifications for bacteria removal:

  • NSF 55 – For UV systems that inactivate or kill bacteria, viruses, and cysts
  • NSF 244 – For any water filters that use mechanical filtration to reduce microorganisms like bacteria in water.
  • NSF 58 – For reverse osmosis system performance. Manufacturers can claim numerous contaminants removed with this certification, including bacteria, viruses, and cysts.

❔ Do Water Filters Remove Bacteria? FAQ

Do reverse osmosis filters remove bacteria?

Yes, reverse osmosis filters are capable of reducing bacteria in drinking water. However, not all bacteria are guaranteed to be removed by RO filtration systems. If you want to be certain that a reverse osmosis system will protect you completely against bacteria, look for third-party test results or certifications for bacteria removal.

Does a water pitcher filter remove bacteria?

No, most water pitcher filters can’t remove bacteria. You’ll need a nanofiber filter, such as the Epic Nano filter pitcher, to remove contaminants as small as bacteria.

Do whole home water filtration systems remove bacteria?

Some whole house water filter systems can remove bacteria, but most can’t. Why? Because bacteria filtration often requires filters with tiny pores, and using this type of filter in a whole home water treatment system would significantly reduce water flow in your home. However, you can use whole house UV systems that treat pathogenic bacteria and other microorganisms with ultraviolet light.

Does a Brita filter remove bacteria?

No, Brita’s filter can’t remove bacteria. Brita only mildly improves water quality by removing chlorine, mercury, cadmium, copper, and zinc.

  • Jennifer Byrd
    Water Treatment Specialist

    For 20+ years, Jennifer has championed clean water. From navigating operations to leading sales, she's tackled diverse industry challenges. Now, at Redbird Water, she crafts personalized solutions for homes, businesses, and factories. A past Chamber President and industry advocate, Jennifer leverages her expertise in cutting-edge filtration and custom design to transform water concerns into crystal-clear solutions.

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