Water contamination can occur naturally or from human activity, according to the Environmental Protection Agency. Once you know which contaminants are in your drinking water you can compare your filtering options. Here’s what the experts at Consumer Reports say you should consider.

A Consumer Confidence Report, or CCR, from your municipality states the levels of contaminants detected in the water and how that compares to the EPA’s drinking water standards. This water-quality report tells you about the water in your town and not necessarily what’s coming out of your own tap. Note that community water systems providing water to 100,000 or more people must post the reports online. The EPA doesn't regulate private wells so a CCR isn't required. 

“Water is very local, and some people have lead pipes in their homes,” says Mae Wu, a senior attorney with the Health Program at the Natural Resources Defense Council. “And there are millions of lead service lines in the U.S. As long as the lead is there, there could be lead contamination.” Lead isn’t the only concern, she adds. Contaminants vary, depending on where you live and whether it’s rural or urban, pesticides or industrial chemicals, for example.

Start by reading your water-quality report, if available, and test your water before buying a filter. Your state or local health department may offer free test kits, and they’re sold at home improvement and hardware stores. The EPA suggests sending samples to a certified lab for analysis. Your local water authority can offer a list of labs, check the EPA’s list, or call their Safe Drinking Water Hotline at 800-426-4791. Here’s what you need to know about water filters.


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Filters are designed to eliminate specific contaminants. To be assured a filter will remove a certain contaminant, the package should say the filter meets NSF-certification for that substance. NSF International is a nonprofit testing lab that also develops standards for the industry. Third party labs that certify products to NSF standards include CSA, UL, and WQA. 

Consumer Reports’ past tests focused on the removal of lead and chloroform, which also indicates how well the filter will remove organic compounds. You’ll see those scores in our water filter Ratings, and click the features & specs tab to see which tested filters are NSF certified for removal of lead and organic contaminants. The NSF “Contaminant Reduction Claims Guide” also offers useful information.

You have to regularly change the filters, or don’t bother buying one. All filtering systems work the same way, with water passing through a removable cartridge filled with a filtering medium such as activated charcoal. Filters can become clogged, and no longer effective. Follow the manufacturer’s recommended schedule for changing them. Some water filters have a light that tells you it’s time, and slower-than-usual filtering may also indicate it’s time to replace the filter.

Factor in the cost of replacing filters. Costs vary by filter type and model. Among carafes, filter cost per year ranges from $32 to $180. Check the features & specs tab in our water filter Ratings to compare annual costs.

Figure out how much drinking water your family uses. A carafe or two might suffice for one or two people, but isn’t ideal for a family that consumes several gallons of water a day. Include the amount of water you use for cooking. Countertop and undersink models can filter lots of water. Our water filter buying guide compares filter types.

Filtering water can be slow with some types. Consider your level of patience and how much water your family uses in a day. Carafe and reverse-osmosis filters generally provide the slowest flow rates and are scored on their own scale. Among faucet mount, countertop and undersink models, the faucet mount filter flows the slowest. You’ll see flow-rate scores for each tested filter in our ratings.

Email questions about water filters to kjaneway@consumer.org.