Get The "Tea" On How To Help Purify Your Water.

It's Good News For Tea Lovers & Lead Haters. Plus, a WOTUS update.

Photo by petr sidorov on Unsplash

We have good news this week for tea lovers in need of a water filter. You can actually brew your way to cleaner water.

In a new study, researchers found that the act of preparing tea naturally helps filter dangerous contaminants out of your drink—particularly heavy metals like lead and cadmium.

“We’re not suggesting that everyone starts using tea leaves as a water filter,” said Northwestern’s Vinayak P. Dravid, the study’s senior author in a statement.

But the research quantifies an effect that may be quietly benefiting tea drinkers worldwide. The science behind this phenomenon is simple: heavy metal ions attach themselves to the surface of tea leaves during brewing and remain trapped there. This adsorption process effectively removes contaminants from your beverage before you consume it.

Tea leaves have a high active surface area, making them excellent at quickly releasing flavor compounds—and capturing unwanted metal particles, according to Benjamin Shindel, the study’s lead author.

What makes this finding particularly significant is the global popularity of tea. You could certainly crush various materials to achieve similar filtration results, Shindel points out, but “tea happens to be the most consumed beverage in the world.”

So, people don’t need to change their habits, as they get this benefit already.

The Brewing Variables

The team didn't just confirm tea’s filtration abilities, but they also investigated how different variables affect the process, exploring how different types of tea, tea bags, and brewing methods impact heavy metal adsorption.

Their methodology was thorough: creating water solutions with measured amounts of toxic metals, heating them to near-boiling, adding various types of tea leaves, and measuring the remaining metal content after brewing.

Several interesting patterns emerged from their experiments:

The bag matters significantly. They examined the differences between loose-leaf and commercially bagged tea. While cotton and nylon tea bags removed virtually no heavy metals, cellulose bags, made from biodegradable wood pulp, proved remarkably effective. Researchers attribute this to cellulose's higher surface area, which provides more binding sites for metal ions.

(We’ll talk about tea bags and microplastics in a moment).

Tea variety plays a minor role. The team tested traditional teas (black, green, white, and oolong) alongside herbal options like chamomile and rooibos. Black tea performed slightly better, especially when finely ground.

“When tea leaves are processed into black tea, they wrinkle and their pores open,” Shindel explained. “Those wrinkles and pores add more surface area. Grinding up the leaves also increases surface area, providing even more capacity for binding.”

Brewing time is the most crucial factor. The longer tea steeps, the more contaminants it removes.

“A quick 30-second steep won’t accomplish much filtration," Shindel noted. But brewing for several minutes, or making overnight iced tea, can remove most or nearly all metal contaminants from your water.

Public Health Implications

The filtration effect varies based on several factors, but researchers estimate that a typical cup of tea (one mug of water, one tea bag, steeped for about 3 to 5 minutes) can remove approximately 15 percent of lead from drinking water—even at concentrations as high as 10 parts per million.

While tea brewing certainly won't solve a water crisis, these findings could have meaningful public health implications.

This research opens interesting avenues for epidemiological studies.

“Across a population, if people drink an extra cup of tea per day, maybe over time we’d see declines in illnesses that are closely correlated with exposure to heavy metals,” Shindel said. “Or it could help explain why populations that drink more tea may have lower incidence rates of heart disease and stroke than populations that have lower tea consumption.”

Now the next time you sit down to enjoy your favorite cup of tea, take comfort in knowing your drink isn’t just warming you up or helping to soothe your soul, but it's helping to purify your water too.

This study was partially supported by the U.S. Department of Energy and the Paula M. Trienens Institute for Sustainability and Energy at Northwestern University.

The Downside Of Tea Bags

A study came out late last year sounding the alarm on tea bags and how they may be shedding billions of microplastics, which are tiny, degraded plastic bits that don’t break down and are suspected to pose a risk to human health.

Researchers tested three different brands of tea bags for exposure.

The plastic bags made of polypropylene, a common tea bag material, released more than a billion particles per milliliter of tea. While paper tea bags made of cellulose and mesh nylon bags shed millions of plastic particles per milliliter.

That’s very concerning!

While many studies have linked chemicals in plastic production with serious problems, such as endocrine system disruption and cancer, scientists are still working to understand the health impacts of ingested microplastics. Learn more about micro and nano plastics here.

I would say use the precautionary principle when you can, which suggests that when you don’t know for certain if there are damaging effects from a substance, especially one that is persistent and toxic in the environment, it is best to err on the side of precaution. It’s better to prevent exposure, rather than try to clean up or cure the negative health impacts of an environmental exposure after it has occurred.

If you want to continue to enjoy the benefits of tea, an easy solution is to use loose-leaf tea with a stainless-steel infuser or a reusable filter made of stainless steel. Loose-leaf teas come in organic varieties and tend to have a more robust flavor. Teabags tend to contain dust and smaller pieces of tea, which can sometimes taste dull or stale.

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Revisiting the “Waters of the United States” (WOTUS)

You may have seen recent headlines about the U.S. EPA removing federal protections for the country's wetlands. Let’s review this law that has been flip-flopping for 50 years, depending on how the brook babbles.

We are once again reviewing regulatory changes that define the “waters of the United States,” or WOTUS. Depending on whose in office, we either expand or restrict the bodies of water subject to federal permitting.

A 50-Year Debate: Defining "Waters of the U.S"

New EPA administrator Lee Zeldin announced last week that EPA will work with the United States Army Corps of Engineers to deliver on the new administration’s promise to review the definition of the WOTUS, saying that the agencies will move quickly to ensure that a revised definition follows the law, reduces red-tape, cuts overall permitting costs, and lowers the cost of doing business in communities across the country.

The former New York Congressman has earned a 14-percent lifetime environmental voting score from the League of Conservation Voters.

But this news comes as no surprise given that the U.S. Supreme Court’s watershed decision Sackett v. Environmental Protection Agency in 2023, dramatically weakened the Clean Water Act by deciding what wetlands deserve protection from pollution.

The case stated that the Clean Water Act’s use of “waters” encompasses only those relatively permanent, standing, or continuously flowing bodies of water forming streams, oceans, rivers, and lakes.

Writing for the 5-to-4 majority, Justice Samuel Alito asserted that the late Justice Scalia’s definition of “waters of the United States” was the proper one: any wetland that does not connect at its surface to another body of federally protected water doesn’t merit the same degree of protection.

As almost any water expert would tell you, Alito’s opinion has no basis in science. Water flows in all sorts of ways: aboveground; below ground; rapidly, down rivers and streams; and slowly, through the cleansing filters of the reeds, soils, and grasses that make up a wetland.

This latest step by the new administration toward weakening regulations in favor of prioritizing economic prosperity has agriculture and business advocates celebrating, while environmental supporters worry about a future flood of water pollution across the country.

You can’t say you want “clean water for all Americans” and then strip away the very rules that help ensure that protection.

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What are your carrots and sticks for the week? Let us know in the comments below!