We wish we could simply tell you "This is THE BEST water filter you can buy"—and send you on your merry way.
But the truth is the “best” water filter for your home depends on two factors that will be different for everyone: the contaminants present in your water, and the style of filter that is most practical for your household. Luckily, once you’ve identified those two things, the rest is easy.
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What's contaminating your water supply?
Thanks to the Environmental Working Group’s new Tap Water Database, you can type in your zip code and find out exactly what contaminants are lurking in your local public water supply. For example, you might find that your municipality is plagued with high levels of agricultural chemicals but that your water is well within safe levels of mercury. This information will help you decide what types of contaminants you want to focus on when shopping for a water filter, since not all filters work the same way or filter out all of the same toxins. (If you have a well, you can buy a well water testing kit like this one to find out what’s in your water.)
How can you filter it out?
Now that you know the contaminants in your water supply, use the EWG’s Water Filter Guide to find a water filter that will remove the contaminants you’re most concerned about. The most important rule of buying a water filter is to choose one that is certified by the Water Quality Association or NSF International, independent organizations that have verified the filter actually gets rid of the contaminants it claims to remove.
When you're shopping for a new filter, it helps to understand the available options in water filter technology. There are a dozen or so different types of water filter technologies available, but the three most important ones you should know are activated carbon, ion exchange, and reverse osmosis. Most water filters will use one or a combination of these three filtration technologies. (You can read more about water filter technologies here.)
Activated carbon filtration: You may know this material by its trendier name, activated charcoal. It's also the most widely used type of water filter. Contaminants chemically bond to the carbon as water flows through the filter, removing them from your drinking water. There are two types of activated carbon filters: granulated activated carbon and carbon block. Carbon block is carbon that is shaped into blocks under high pressure and is typically considered more effective because it has more surface area for contaminants to bond to. Granulated activated carbon filters are comprised of small bits of carbon and are generally less effective (though they work better when water moves through slowly.)
Ion exchange filtration: Ion exchange works by passing water over a resin that replaces undesirable ions with more desirable ones. This technology is most commonly used for water softeners. Lots of filters use ion exchange filtration in conjunction with activated carbon.
Reverse osmosis filtration: Reverse osmosis is the king of water filtration systems. It forces water through a semipermeable membrane, blocking all particles larger than water molecules, and therefore captures many toxins not trapped by carbon filters. Reverse osmosis filters often do incorporate a carbon filter component, too, however, in order to capture chlorine, trihalomethanes, and VOCs that can slip past the membrane. It’s important to note that reverse osmosis systems waste a lot of water—they typically use up three to twenty times more water than they produce, according to the EWG, which is why it is recommended they only be used for drinking and cooking.
Water filter options
Choose the style of water filter that works best for your needs—whether that’s a big reverse osmosis system installed under the sink, or a simple water pitcher with a built-in filter. Below, we weigh the pros and cons of each.