What Does a Refrigerator Water Filter Remove? NSF Ratings and Replacement Guide
Short answer: most refrigerator water filters use activated carbon, and their main job is to make water taste and smell better. Many also reduce certain chemicals such as lead, but they are generally not designed to remove germs. The way to know what a particular filter removes is its NSF certification: check the listing or label for the standard number and the exact substances it is certified to reduce.
What a refrigerator water filter does (and doesn’t) remove
According to the CDC, pitcher filters and filters built into refrigerators often use activated carbon, mainly to improve taste and smell rather than safety. Carbon filters like these are also used to remove heavy metals such as lead. What a filter actually catches depends on the size of its pores, the size of the substance and its electric charge, so two filters that look alike can perform very differently.
- Usually reduces: chlorine taste and odor; some filters are also certified for lead and other listed chemicals.
- Usually does not remove: bacteria and viruses. Removing bacteria takes an absolute pore size of 0.3 micron or smaller (or ultrafiltration, nanofiltration or reverse osmosis); viruses take nanofiltration or reverse osmosis.
- Removes some good things too: filters can take out chlorine (which keeps germs down in tap water) and fluoride (which helps prevent cavities).
From CDC, “About Choosing Home Water Filters” (reviewed April 2024), read October 24, 2026.
NSF standards to look for on the listing
NSF International is an independent organization that writes public health standards for products. A filter certified to a standard has been tested for specific claims, and you can look up a product in NSF’s certified-products database. The standards the CDC lists for water treatment:
| Standard | What it covers | What it means for a fridge filter |
|---|---|---|
| NSF/ANSI 42 | Taste and odor (aesthetic effects) | The baseline for most fridge filters: chlorine taste and odor, and particulates |
| NSF/ANSI 53 | Health-related contaminants, including cyst reduction | Look for this when you want reduction of things like lead or cysts; check which substances are named |
| NSF/ANSI 58 | Reverse osmosis systems | Under-sink systems, not fridge cartridges |
| NSF/ANSI 62 | Distillation systems | Countertop distillers, not fridge cartridges |
The certification is only as useful as the claims listed under it. A real label names the standard and each substance, for example “certified against Standard 42 for chlorine taste and odor; against Standard 53 for the reduction of lead and cysts.” “Meets NSF standards” or “tested to” is not the same as being certified.
Standards list and label example from CDC, “About Choosing Home Water Filters”, read October 24, 2026.
Do you need a filter at all?
The CDC’s advice is to start with what is actually in your water, not with taste. Harmful germs and chemicals often don’t change how water looks, tastes or smells, while harmless substances such as some sulfur compounds can make water smell bad.
- City water: read the annual water quality report your utility must publish; it shows whether harmful germs or chemicals were found.
- Private well or rainwater: test at least once a year, and again if color, taste or smell changes. Your health department can point you to a state-certified lab.
If your water is already free of harmful germs and chemicals, a fridge filter is mostly about taste. If testing shows a specific contaminant, buy a filter certified to reduce that exact substance, or a different kind of treatment system if a carbon filter can’t handle it.
Changing your fridge filter
- Follow the replacement interval in your refrigerator’s manual or on the filter. The CDC notes every filter has to be maintained and changed on schedule to keep working and to stop germs from growing in it.
- Match the cartridge to your fridge: filters are model-specific. Copy the part or model number from your old cartridge or the manual and compare it to the listing before you order.
- Wear gloves and wash your hands after changing a filter. If you have a weakened immune system, the CDC advises having someone else change it.
Quick checklist before you buy a replacement filter
- Old cartridge’s part number or fridge model number written down
- Listing confirms it fits that exact model
- NSF certification named (Standard 42 at minimum)
- Standard 53 claims checked if you want lead or cyst reduction
- Specific substances listed, not just “meets standards”
- Replacement interval noted (set a reminder)
Shop refrigerator water filters on Amazon
Check each filter’s compatible refrigerator models, part number and NSF certification claims on the listing.
Keep reading
See all water filters and refrigerators, or read our refrigerator buying guide.
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