play video

Water Filters

Water filters are necessary to remove or reduce the myriad chemicals that contaminate our nation's drinking water, some of which are linked to cancer and endocrine disruption.

Healthiest Water Tips

  • Choose a filter certified by NSF International or the Water Quality Association

  • Change filters on schedule

  • Use EWG’s Water Filter Buying Guide

  • Use BPA-free reusable water bottles

Do’s & Don’ts

Dirty Details

No matter where you live, or how pure you think your water is, your tap water likely contains chemicals you should not be drinking. In fact, a 2017 EWG investigation of drinking water data found more than 250 chemicals in U.S. public water systems. More than half of these chemicals are not regulated by the Environmental Protection Agency and are not subject to any safety standards

Know Your Local Contaminants

To learn what’s in your tap water, check EWG’s Tap Water Database or your local water utility’s website for its drinking water quality report, which contains information on water testing. Utilities are required to produce these reports annually.

Below are a few common contaminants of concern:

  • Trihalomethanes and haloacetic acids. These contaminants, which have been linked to cancer, are routinely found in drinking water, sometimes above EPA-regulated limits.
  • Arsenic. It is a known human carcinogen that can cause bladder, lung and skin cancer, as well as harm to the skin and lungs. Arsenic can come from natural, industrial and agricultural sources. It is released in emissions from industrial processes, and it is also used as a wood preservative and a pesticide.
  • Perchlorate, the explosive component of rocket fuel. It remains unregulated by the EPA despite widespread contamination. There is strong evidence linking the chemical to thyroid problems.

Find a Filter

Although there are hundreds of brands and models of home water filters, they usually come in six main forms—pitcher or large dispenser, faucet-mounted, faucet-integrated, on-counter, under-sink or whole-house. All filters rely on a small number of technologies: carbon or activated carbon, reverse osmosis, deionization, ion exchange, mechanical filters, ozone, ultraviolet and water softeners.

Carbon filters, a common choice, are affordable and are effective in removing or reducing many common water contaminants, like lead and byproducts of treatment processes. Reverse osmosis filters are also popular and remove contaminants that carbon filters can't eliminate, like arsenic and the rocket-fuel chemical perchlorate, but they can be quite expensive.

Look for a filter certified by NSF International or the Water Quality Association, both of which are independent, third-party organizations. These trusted certification bodies test water filters’ capabilities for reducing contaminants. And use EWG’s Water Filter Buying Guide to decide which filter will work best for your home.

Infant Formula Safety

If your water is fluoridated, it is safest to use a reverse osmosis filter for tap water that goes into your baby's formula, as fluoride can damage developing teeth. For the same reason, if you choose bottled water for your infant, make sure it's fluoride free.


  1. NSF International, Residential Water Treatment Devices. Available at
  2. Brian Bienkowski, New Report: Unregulated Contaminants Common in Drinking Water. Environmental Health News, 2013. Available at
  3. Environmental Working Group, EWG’s Bottled Water Scorecard, 2011. 2012. Available at
  4. Environmental Working Group, EWG’s Guide to Safe Drinking Water. 2016. Available at
  5. Environmental Working Group, EWG’s Updated Water Filter Buying Guide. 2017. Available at
  6. Paul Pestano, Finding a Water Filter that Works for You. Environmental Working Group, 2013. Available at
  7. Dave Andrews, Is Your Drinking Water Contaminated with Toxic Non-Stick Chemicals? Environmental Working Group, 2015. Available at
  8. Environmental Working Group, EWG’s Tap Water Database. 2017. Available at
  9. Renee Sharp and Paul Pestano, Water Treatment Contaminants: Forgotten Toxics in American Water. Environmental Working Group, 2013. Available at
  10. The New York Times, Toxic Waters. 2010. Available at