How CR Tests Water Filters
We test a water filter’s flow rate by seeing how long it takes to filter one quart of water. We also give each filter a "clogging" score, based on how much a filter’s flow rate slows down over the stated life of the cartridge.
NSF International and the American National Standards Institute develop filtration standards. If a manufacturer claims that a pitcher meets NSF/ANSI standards for removing specific contaminants, such as chlorine, lead, and PFAS, we verify those claims.
We also check claims of flavor and odor reduction by spiking spring water with commonly found compounds that can make the water smell and taste like a sewage treatment plant, damp soil, metal, or a swimming pool. A trained panel of professional tasters evaluates how successful the filters are at removing those flavors and odors. The best-performing filters work well enough that most people wouldn’t be able to discern a palatable difference between the filtered water and pure spring water.
What's in Your Water?
The Environmental Protection Agency requires community water suppliers to provide a Consumer Confidence Report to customers every July. A CCR states the levels of regulated contaminants detected in the water and how they compare with the EPA’s drinking water standards. If you rent an apartment, contact your building manager or local water company for a copy.
Community water systems providing water to 100,000 people or more must post the reports online. If you use well water, you won’t have a CCR because the EPA doesn’t regulate private wells. In that case, check with the Centers for Disease Control and Prevention for information on well testing and treatment.
The water quality report tells you about the water delivered to your house, but if it was built before lead-free pipes were mandated in 1986, you may want to do your own tests for lead. There’s no safe level of lead exposure, according to the EPA.
Some advocacy groups and consumers feel the same about PFAS (per- and polyfluoroalkyl substances), a group of more than 12,000 synthetic chemicals that persist in the environment and are thought to be detrimental to human health. According to a 2023 study by the U.S. Geological Survey, at least 45 percent of the nation’s tap water is contaminated with PFAS, which are linked to obesity, cancer, learning delays in children, and thyroid disease. In the 2021 CR-Guardian study, almost every test sample had measurable levels of PFAS, and more than 35 percent exceeded the maximum safety threshold specified by CR scientists and other health experts. The Environmental Working Group, an advocacy organization, estimates that more than 3,000 communities in all 50 states and two territories have drinking water contaminated with PFAS.
Tap water crises, state legislation, and public awareness nudged the EPA to propose new federal limits on six different PFAS in drinking water, including PFOA and PFOS, two of the most studied.
Few utilities currently test for PFAS. If yours doesn’t, or if you use well water, you can get your water tested by an EPA-certified lab like SimpleLab or WaterCheck from National Testing Laboratories. But be prepared to shell out a few hundred dollars. In addition to its list of certified labs, the EPA offers a Safe Drinking Water Hotline at 800-426-4791. For more on testing your water, see our interactive guide.
How to Choose a Water Filter
Once you know what’s in your tap water, you can find a filter that best suits your needs.
If tests reveal no harmful contaminants and the only problem with your water is taste and/or odor, check CR’s water filter ratings for filters that score high in our tests for flavor/odor reduction.
If contaminants are found, the best way to remove them is with a water filter that’s certified to remove those specific contaminants. That means the filter is independently tested and found to comply with an accepted standard specific to the contaminants and is subject to follow-up testing by the certifying agency to ensure that the product that consumers purchase will perform the same as the product that was tested.
Look at the filter’s packaging for a stamp or seal confirming which contaminants it’s certified to remove. Third-party labs that certify products to NSF/ANSI standards include the National Sanitation Foundation itself, the Water Quality Association (WQA), and the International Association of Plumbing & Mechanical Officials (IAPMO).
Our ratings for water filter pitchers and under-sink, faucet-mounted, and countertop water filters identify which are certified for the removal of lead, chlorine, and PFAS. Our ratings of reverse-osmosis water filters indicate which ones passed CR’s tests for the removal of lead and cholorform, an indicator of chlorine.
All filters must be replaced periodically to function effectively. Our ratings allow you to compare the annual cost of replacing filters for each product. For example, replacement filters for the pitchers we test range from $16 to $78. You’ll also see which models have a filter-life indicator, a handy feature that tells you when it’s time to change the filter.
Filtering Your Choices
Water filter pitchers are one of the most widely used types of water filters, but there are other filtration systems available for the home. Factor in your budget, your water consumption, maintenance, and, most importantly, the contaminants found in your water before purchasing a new filter.
Water Filter Pitcher
Water pitchers are great if you’re on a budget, you don’t have the space to install a permanent filter, or you’re renting. But you do need to keep filling them over and over while other types filter constantly. The best water pitcher model we’ve tested does a stellar job of removing chlorine without sacrificing cartridge life or flow rate. Some others are slow, prone to clogging, or have a short filter life. A small pitcher stored in the refrigerator might suffice for one or two people, but a large size—or an installed option that filters continuously—may be more convenient for a family that consumes several gallons of water a day.
Price of tested filters: $17 to $54.
Faucet-Mounted Water Filter
If you’re looking for easy installation, these are a good choice for filtering drinking and cooking water. Simply unscrew the aerator from the threaded tip of your faucet and screw on the filter. Faucet-mounted filters let you switch between filtered and unfiltered water. On the downside, they slow down water flow and don’t fit on all faucets, including those with a pullout sprayer.
Price of tested filters: $15 to $31.
Countertop Water Filter
These filters are also easy to install. Just remove the faucet aerator, then screw the filter hose onto the faucet. This also makes them handy for renters, who might not have a landlord’s okay to do more significant plumbing modifications. Basic models use carbon filtration, while more costly units may use reverse osmosis or ultraviolet light to guard against more serious contaminants. CR’s tests found that countertop filters are less likely to clog than pitcher filters or faucet-mounted filters, but they can clutter a countertop, and they don’t fit all faucets.
Price of tested filters: $80 to $1,179.
Under-Sink Water Filter
Under-sink filters are arguably the most convenient option once you get past the more difficult installation. They don’t clutter the counter (but do take up space under the sink) and they look better than the alternatives. Like countertop filters, these can filter lots of water. But installation may require professional plumbing modifications and drilling a hole through the sink or countertop for the dispenser.
Price of tested filters: $93 to more than $500.
Reverse Osmosis Water Filter
If you’re facing more serious water contamination issues, you may need the more powerful filtration of a reverse osmosis system. Using standard household water pressure, water is forced through a semipermeable membrane, then through filters. Reverse osmosis filters can remove a wide range of contaminants, including dissolved solids. But they can be extremely slow, rob cabinet space, and typically create 3 to 5 gallons of wastewater for every gallon filtered. You must sanitize them with bleach periodically, and the membrane and filters must be replaced, per manufacturer’s recommendation.
Price of tested filters: $155 to $2,200.
Refrigerator Water Filter
Water-and-ice dispensers are common on French door, bottom-freezer, and side-by-side refrigerators. The water line typically runs through a filter inside the refrigerator. Most filters can be easily replaced by simply pushing and twisting. A replacement filter can cost $50 or more, and you’ll need to change it every six months or so. Third-party water filters are widely available at a lower cost but may be less reliable or effective. Depending on the particular filter, fridge filters can reduce many of the same contaminants as a countertop or under-sink filter.
Consumer Reports is not currently testing refrigerator water filters.
