Shop online for a refrigerator water filter, and you’ll notice a big price range for what seems to be the same filter.  At the high end are brand-name water filters offered by the refrigerator manufacturer—Kenmore, Whirlpool, Samsung, LG, Frigidaire and other familiar brands.

On the low end are brand-name water filters listed by sellers other than the manufacturer, as well as off-brand water filters sold as being compatible with a brand-name water filter.

So what’s the difference? Quality and reliability—and in some cases, authenticity.

The Risk with Cheap Water Filters

It’s tempting—so tempting—to buy the lowest-priced water filter. Unfortunately, that’s a risky strategy, because you can’t be sure that the water filter actually removes contaminants that might be in your water supply. Nor can you be sure that the filter is constructed to the standards of the original manufacturer to be free of BPA, to deliver water at the promised flow rate and to filter the promised number of gallons before you have to replace it.

Here, briefly, is why not to buy an off-brand filter or a brand-name filter sold by anyone other than the manufacturer:

  • Off-brand filters—those sold as compatible with brand-name filters—don’t go through the same testing the brand-name filters do. While off-brand filters can be tested for contaminant removal and structural integrity, they aren’t tested for how well they work within the refrigerator system itself. And they don’t always remove as many contaminants as a brand-name filter does.
  • Counterfeiters have flooded online marketplaces with low-quality water filters that look like trusted brands. Because you can’t always tell a fake by looking at it, the only way to be sure you’re getting an authentic filter is to buy it on the manufacturer’s site or from the manufacturer’s brand store on a marketplace site.

A Quick Look at Refrigerator Water Filter Certification

Independent non-profit organizations test water filters to make sure the filters actually remove the contaminants as claimed. They also test that the filters are structurally sound and meet minimum requirements for water flow.

The most widely known certification organization is NSF International. Certified filters bear the NSF logo, and don’t say “tested to NSF standards”.

Three NSF certification standards apply to water filters.

Standard 42 for aesthetic effects. The water filter removes microscopic particles of dirt, chlorine taste and odor, and some lead. Standard 42 is divided into six classes based on the size of the particles the filter traps. All classes except classes I and II also filter out the Cryptosporidium cyst, a parasite that poses a serious health risk for people with compromised immune systems.

Standard 53 for health effects. The water filter traps more lead than filters rated for standard 42, as well as other heavy metals. It also removes volatile organic compounds (VOCs), asbestos and Cryptosporidium cysts.

Standard 401 for emerging contaminants. The water filter removes at least one of the 15 chemicals in a new contaminants category. These chemicals—mostly medications and pesticides—have been found in trace amounts in some drinking water supplies. They’re called “emerging” contaminants because they’re a new cause of concern. The health effects of these contaminants have yet to be determined.