EWG's Tap Water Database


Water Filter Buying Guide: Frequently Asked Questions

Why didn't you include [X] filter?

EWG included all household filters that were certified by NSF International or the Water Quality Association as of January 2017. These third-party certifiers conduct tests to certify that water filtration systems meet strict standards and are effective at reducing contaminants. Our Water Filter Guide does not include any commercial (restaurant, hotel, etc.) water filtration systems. If you are looking for a particular water filter and it's not in the guide, it is likely that NSF International or WQA had not certified that brand/model when we were developing the database. You may find more details about these two certification programs here and here.

Why don't you have an option to filter out [X contaminant]?

There are two possible answers. The first is that EWG does have an option to filter out the contaminant that you are interested in, but you may not be looking in the right place. If you go to the bottom of the page and click on the "see more contaminants" link right above the search button, you will be provided with a much more extensive list of contaminants from which to choose. The contaminant you are interested in may be found on this list.

If you still cannot find a filter for the contaminant, this is because there was no filter certified by the NSF International or WQA available on that is certified to reduce this contaminant as of January 2017.

Why don't you address the effectiveness of the filter?

Water filters vary widely in quality and in what contaminants they will reduce. Consumers need to do their research to make sure they are getting what they are paying for. There are many different kinds of water filters with many pros and cons. There is no single best water filter for everyone. EWG's guide is designed to help steer people through the complicated process of choosing the best water filter for themselves, depending on what contaminants are in their water and which of those they are most interested in reducing. We cannot give each filter a single rating because the efficacy of the filter will depend on what contaminant you are trying to filter out. In addition, there are other factors such as cost, energy use and water use that vary between different filter types, but these factors are more important to some consumers than others.

What's the best water filter?

There isn't a single best answer. Carbon filters remove fewer contaminants than reverse osmosis filters, but are cheaper and use less energy and water. Reverse osmosis filters are more effective at removing many kinds of contaminants, but are more expensive, require more maintenance, and require much more energy and water to function. Water softeners are great for dealing with hard water problems, but won't remove most contaminants. Ultimately, choosing which water filter is right for you and your family is really a personal decision.

Why do you have links to

EWG fully supports consumers buying water filters from retailers of their choice, so we featured several retailers in the 2017 Water Filter Guide, including small businesses and in some cases, even the water filter companies' official websites. We chose Amazon as one of the featured retailers because of its wide range of available household filters, and because EWG participates in the Amazon affiliate program. Additionally, we know that many consumers are looking for the convenience that large online retailers such as Amazon provide. Via the Amazon affiliate program, EWG gets a small donation for every purchase made on Amazon through our website link.

I represent a water filter company. How can I be included in your guide?

EWG's water filter guide contains filters that are certified by either NSF International or WQA to reduce one or more contaminants. To be included in future versions of this guide, EWG recommends getting your company's filters certified by the either or both of these third-party certification bodies. You may find more details about these two certification programs here and here.