Step-by-step guide to selecting a home tap water filter

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Find the right filter for your water – and budget

1. Find out what’s in your tap water.

To see what contaminants your water contains, search EWG’s Tap Water Database for your ZIP code or the name of the water utility that supplies your water. (Note that a community’s water may be supplied by more than one water utility. The reverse is also true: A single water utility may supply multiple communities.)

2. Compare filter types.

A table showing which water filter types – activated carbon, reverse osmosis, and ion exchange – can reduce levels of contaminants specific to your water will appear at the bottom of your water system page.

Some contaminants may be difficult to remove, or there may be just one technology that effectively removes or reduces the levels of a specific chemical. For example, reverse osmosis is the only type of filtration certified to remove nitrate and perchlorate.

When you are looking through the page with information about your community water system, you can click on the “Water Filter Guide” button under “Take Action” for more information about water filtration options.  

3. Choose a filter.

EWG’s Water Filter Guide can help you identify the type of filter that is right for you.

There are several factors to consider when you pick a water filter. One is cost: Filters vary in price depending on the technology they use. The layout and size of your kitchen may be another when it comes to picking a countertop, faucet-mounted or under-sink filter. See this EWG infographic, “The Ins and Outs of Water Filters.”

When searching for a specific filter, keep in mind even filters of the same type can vary in their capacity to reduce the levels of specific contaminants. To ensure that a filter can remove a particular contaminant, check that it has been certified to do so by an independent third-party certification company.

4. Maintain the filter.

To make sure your filter functions properly, follow the manufacturer’s recommendations for cartridge replacement and maintenance. Bacteria can grow on carbon filters that are not replaced according to instructions.

Find your water

Choosing a water filter

Once you know what’s in your water, consider which filters remove which ingredients. While most will vary depending on the make and manufacturer, there are some general guidelines to consider.

Pitcher filter

If you’ve been relying on a pitcher filter to clean your water, you may want to read the fine print. Pitcher filters typically reduce only a few contaminants (such as chlorine), plus the water sits in plastic for an extended period of time and may pick up chemicals from the pitcher itself! Though inexpensive, pitchers are effective mainly at improving the taste and odor of your water and will leave many contaminants of concern. Similarly, the simple filters in water-dispensing refrigerators, besides wasting electricity, remove a relatively small number of contaminants.

Faucet-mount filter

Some faucet-mount filters remove a decent number of contaminants. Again, be sure to read the fine print to see they’re removing what you want them to, as filter performance varies widely. Though faucet mount filters are inexpensive and easily replaced without special skills, if you look carefully at how long a filter lasts and replacement filter costs, you may find that a more effective filter – though initially somewhat more expensive – does not cost much more in the long run.

Countertop water filter

Countertop filters don’t take up space under your sink, and can either hook up to your faucet or be freestanding, gravity-fed filters. Neither requires a plumber to install. The advantage of a filter hooked up to your waterline is that you don’t have to refill a filter container constantly. But a gravity-fed filter is a smart investment because it can purify water in an emergency situation, even when there’s a problem with the water supply or if the power goes out. In a power outage, municipal water supplies can’t maintain water pressure and well pumps will stop working without a backup energy source.

Maintaining countertop filters is also easy and usually requires no special tools. For the Berkey Light water filter (pictured above), maintenance takes less than ten minutes and may only need to be done after several months or even years—depending on the amount of sediment in your water. Replacement filters cost about $160 and filter 3,000 gallons of water. The Berkey Light is also BPA free and portable, making it easy to take on camping trips or set on the deck in summertime.

Undersink filter

An undersink filter makes sense when counter space is in short supply, and like the plumbed-in, countertop filter, an undersink filter does not require refilling. However, like the countertop model, the undersink filter may not work in an emergency situation.

Reverse osmosis

While very effective at removing contaminants, reverse osmosis (RO) filters are also expensive and waste a good deal of water – 3 or more gallons for each gallon you get! And because they rely on electricity, they won’t filter water when the power goes out. Additionally, they remove beneficial minerals that some speculate can cause health issues when RO water is consumed long-term.