Brewing Tea Can Remove Toxic Metals From Water, Study Suggests

Researchers have linked tea drinking to lower mortality risk, cardiovascular disease, and type 2 diabetes. Now, a new study suggests that one of the world’s most consumed beverages has another benefit: purifying water.

The study, published Feb. 24 in ACS Food Sciences & Technology, found that tea can remove toxic heavy metals like lead and cadmium from drinking water. The substances were adsorbed (became stuck to the surface of) loose-leaf tea or tea bags and eventually removed from the cup. 

“It appears that brewing tea may help passively reduce heavy metal exposure and offer a simple and accessible remediation method,” Kantha Shelke, PhD, principal at the food science and research firm Corvus Blue LLC and lecturer at Johns Hopkins University, who wasn’t involved in the study, told Health. “Given tea’s global popularity, this practice requires no lifestyle changes or additional technology, making it an easy public health intervention.”

Study author Vinayak P. Dravid, PhD, a Northwestern University engineering professor, researches and develops a sponge with an outer layer that can clean environmental pollutants. While working under Dravid, then graduate student Benjamin Shindel, PhD, another study author, had a thought: Could teabags also act like a coating, filtering out contaminants?

Shindel, Dravid, and their colleagues decided to find out. 

First, they created water solutions containing heavy metals like chromium, zinc, copper, and aluminum. They also included cadmium and lead, which are particularly toxic. Lead can cause damage to the brain and central nervous system, while cadmium can interfere with kidney function, bone health, and more.

The team heated the solutions to below boiling temperatures and added either loose-leaf tea of various sizes or leaves in different commercial bags. They steeped the tea for varying amounts of time, from seconds to 24 hours.

Then, they measured the concentration of heavy metals left in the tea.

Researchers found that a “typical cup” of tea could remove about 15% of lead from drinking water, even when levels were as high as 10 parts per million to start. A typical cup, in this case, is a mug with water and a tea bag brewed for three to five minutes.

Cotton and nylon bags didn’t adsorb much metal—but cellulose bags did. Ground tea, especially black tea leaves, was slightly better at capturing metal ions than whole leaves. That’s likely because these varieties have higher surface areas, providing more space for heavy metal ions to stick to.

One factor majorly influenced filtering abilities: how long the researchers steeped the tea. “Steeping time is the major consideration in the performance and how much metal you’re removing from your cup of tea,” Shindel told Health. “Even though there are differences between green and black tea, the difference between brewing it for two minutes and four minutes, or four minutes and 10 minutes, is much larger.”

Several studies have noted high levels of heavy metal contamination in teas and tea plantations. However, the authors say their findings offer reassurance that the heavy metals attach to the tea leaves and don’t dissolve into the water.

Shelke called the study “brilliant” and said it highlighted “the potential of tea consumption to passively reduce heavy metal exposure.”

Limitations

While Shelke noted that the study is a “very good start” to understanding the decontaminating properties of tea leaves, there were a few limitations.

The researchers used deionized water, which may not accurately represent a real-world scenario because various tap water ions like calcium, magnesium, and copper also affect adsorption. The scientists also measured only a limited number of teas and tea bag materials.

“To fully understand this effect, it would be valuable to compare different tea formats and brewing methods—such as the standard three-minute dip, the longer steeping times common in Chinese tea preparation, or the vigorous boiling method used in Indian chai,” Shelke said. “These variations could offer deeper insights into how tea interacts with heavy metals and enhances filtration.”

Whether it makes sense to try this at home depends on where you live and whether you already use a filtering system. For many people, brewing cups of tea for decontamination purposes wouldn’t be worth the effort.

“But across the population, if you’re looking at, you know, millions of people getting one or two percent less metal from their drinking water, you could start to see an effect,” Shindel said. “Lead accounts for about one percent of the total global burden of disease.”

Dravid envisions future public health initiatives, such as campaigns encouraging people to decontaminate their water, one cup of tea at a time, or the development of teabags with better metal adsorption properties.

“Imagine, perhaps down the road, there might be tea leaves coupled with something of a sponge,” Dravid said. “That’s good motivation for us to innovate.”