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correction

A previous version of this article incorrectly said that the Brita pitcher with an elite filter and the brand's faucet system do not filter for microplastics. Both the filter and the faucet system are certified to remove Class I particles, including microplastics between 0.5 microns and 1 micron. The story has been corrected.

Q: How do I find out the quality of my tap water in Fairfax, Va., and what is the best way to filter out microplastics? I rent, so I can’t do under-the-sink or over-the-faucet filters, which I understand are the best. Our faucet tap is a hanging one with a spraying feature.

A: You’re smart to start by asking what’s in your water before you shop for a filter because different filters take out different things. Once you know what’s in your water, you can select a filter that takes out what you don’t want to drink. NSF, an independent testing and standards-setting organization that started as the National Sanitary Foundation, has a web page with links to specific filters based on some of the most common chemicals of concern, such as lead. Filters that take out microplastics are in a different category, “401 Emerging Compounds and Contaminants.” Filters listed there remove at least 85 percent of microplastics ranging from 0 to 80 microns in their largest dimension.

Finding out what’s in your water is relatively simple. The Environmental Protection Agency requires all community water suppliers to provide a detailed analysis, known as a Consumer Confidence Report, to customers every July. Fairfax, like many other water suppliers, has posted its 2024 report online. Read the report to find out the levels of lead, nitrates, salts and even uranium in the water where you live. Fairfax Water tests for 285 compounds; the 2024 report says most of these were undetectable.

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The plastic problem

But the tests don’t cover microplastics, which refers to particles smaller than 5 millimeters long, about the size of a pencil eraser. Obviously, you wouldn’t expect to see bits of plastic that size coming out of a tap, but microplastics can also be much smaller. EPA researchers set the lower limit at 1 nanometer (for comparison, an average human hair is about 80,000 nanometers wide). Particles smaller than 1 nanometer are usually called nanoplastics.

Some microplastics are manufactured in a small size for use in consumer products, but a lot of what is now in the environment worldwide comes from breakdown of the plastics that seem to be used for everything these days, including construction materials, food wrappers and clothing made of polyester or acrylic. Rather than decomposing as they age, plastics break up into smaller and smaller particles. Dryer lint, shredded plastic tarps and bits of discarded food wrappers get into the air and soil and eventually wash into streams and rivers and wind up in oceans — and in drinking water. Microplastics have even been found in well water.

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Yet microplastics aren’t tracked in the annual reports water agencies send to their customers. The word does not even appear in the 2024 Fairfax report. Susan Miller, public affairs officer for Fairfax Water, said that’s because there is no EPA-approved testing protocol or standard for microplastics. The EPA is working on that and began giving grants in 2018 to fund research into ways to identify microplastics in drinking water, with the aim of developing testing methods that are quicker and easier than the complicated laboratory analysis needed now. Other researchers are focusing on possible health effects from ingesting microplastics.

Once there is a good way to test and a better understanding of what level of microplastics should be allowed, water agencies will probably include that information in their reports, just as they are beginning to do for another emerging area of concern: “forever chemicals” known as PFAS, for poly- and perfluoroalkyl substances.

Filter options for plastic

In the meantime, one way to select a filter that will minimize your exposure to microplastics is to go by the size of the particles it removes. There is no mandatory standard, but two independent organizations — NSF and the American National Standards Institute, known as ANSI — have established voluntary standards for drinking water and a certification process. Standard 42 limits aesthetic issues — ones that affect the taste, smell or clarity of water — while Standard 53 details chemicals that have health consequences. Standard 42 puts particles into six size ranges. Class I particles are 0.5 microns to 1 micron, Class II are 1 to 5 microns, on up to Class VI, which are bigger than 50 microns.

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Researchers still don’t understand how microplastics affect human health. So for now, filter manufacturers can treat plastic particles like any other particles, covered under Standard 42 as an aesthetic issue. Any good filter should come with a data sheet that details what it filters out. To avoid drinking microplastics as much as possible, get a filter that removes Class I particles.

Under-the-sink and over-the-faucet filters are great because they filter all the water that comes out of the tap. But renter-friendly options for filtering drinking and cooking water also exist.

Brita, which sells a range of filter types — including water bottles, countertop dispensers and faucet add-ons — lists microplastics on the data sheet for only one of its filters: the Brita Hub, a countertop model. It is certified to remove 99.9 percent of microplastics and other Class I particles. (With a nine-cup reservoir, the Brita Hub lists for $119.99. With a 12-cup reservoir, it’s $179.99. The filter needs to be changed twice a year, at a current cost of $29.99.) A countertop model would present no issues to a renter.

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The Brita pitcher with an Elite filter and Brita’s Elite faucet system also are certified to remove Class I particles, including microplastics between 0.5 and 1 microns.

Some Brita filters would not be a good choice for removing microplastics. The company doesn’t claim any particulate reduction for its standard filter or its reusable filter. And the Brita Bottle, a water bottle with a built-in filter, and the Brita Stream, a pitcher filter that lets you pour water without delay after you fill the container, are certified to remove only Class VI particles.

Have a problem in your home? Send questions to localliving@washpost.com. Put “How To” in the subject line, tell us where you live and try to include a photo.

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