What's Best: A Whole-House or Undersink Water Filter?

If your goal is to have filtered water to drink and cook with, an undersink water filter is probably all you need. Filters certified to the NSF/ANSI 42 standard effectively remove odors and off-tastes.

Water filters certified to the NSF/ANSI 53 standard remove lead and other contaminants. If your annual water-quality report shows that you have a wide range of contaminants or bacteria in your water, an undersink reverse osmosis water filter is your best bet.

Whole-house water filters (different from softener systems for hard water) are best for removing large sediment, such as sand and iron. (The latter can stain sinks and clothing.) These water filters can also improve the taste of your water, but the most basic ones don’t filter for the contaminants that undersink water filters do.

"Some advanced whole-house purification systems can remove potential hazards such as volatile organic compounds [VOCs], pesticides, and heavy metals, but they're expensive—and can be overkill," says John Galeotafiore, associate director of product testing at CR. For example, you probably don’t need filtered toilet water.

If you're worried about sediment as well as contaminants in your water, Galeotafiore recommends pairing a basic, less expensive whole-house water filter with an NSF/ANSI-certified point-of-use water filter for the water you ingest.

Check our water filter buying guide for more information and our water filter ratings to see how each model we test performs. Below are a few undersink water filters from our ratings, in alphabetical order.

Editor’s Note: This article also appeared in the May 2020 issue of Consumer Reports magazine.

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