Brewing Tea May Naturally Help Remove Lead from Drinking Water, New Study Finds
Tsara Tea – For tea lovers, there’s now another reason to enjoy that daily cup — it may be quietly helping purify your water.
Researchers at Northwestern University have discovered that brewing tea can naturally remove heavy metals like lead and cadmium from water, thanks to a process called adsorption. In simple terms, the tea leaves act like a sponge, trapping metal particles before you take your first sip.
How Tea Removes Heavy Metals
When tea leaves steep in hot water, their surfaces — full of microscopic wrinkles and pores — attract and hold on to certain contaminants. These heavy metal ions stick to the leaf surfaces, which prevents them from staying in the liquid you drink.
“It’s not that tea was designed to be a water filter,” said Professor Vinayak P. Dravid, one of the study’s authors. “But its natural structure gives it a high surface area, which makes it good at binding metal particles.”
The study, published in ACS Food Science & Technology, tested a variety of teas including black, green, oolong, white, chamomile, and rooibos. Researchers found that while all teas showed some ability to remove metals, black tea — especially when finely ground — was slightly more effective.
The Role of Tea Bags
Interestingly, the type of tea bag also made a difference. Bags made from cellulose (a natural plant fiber) removed more heavy metals than cotton or nylon bags. Nylon bags, already under scrutiny for potentially releasing microplastics, performed the worst in terms of contaminant removal.
If you’re looking to maximize any possible water-purifying benefits, you might want to choose loose-leaf tea or cellulose-based bags.
Steeping Time Matters
Of all the factors tested, steeping time turned out to be the most important. The longer the tea was brewed, the more metals it removed.
For example:
- A quick 30-second steep removed only a small fraction of metals.
- A typical 3–5 minute brew removed a noticeable amount.
- Long brews (like overnight cold-brews) removed close to all detectable lead from the test water.
This suggests that if you enjoy making iced tea or letting your tea steep for longer, you could be increasing its natural filtration effect.
How Much Does It Actually Remove?
In the experiments, tea brewing was able to remove about 15% of lead from water at levels as high as 10 parts per million (which is extremely high and unsafe for drinking). While no one is suggesting tea should replace proper water filtration, the study points out that even a small reduction in heavy metal exposure could have public health benefits — especially in areas with older plumbing or mild contamination.
For context, the U.S. Environmental Protection Agency’s action level for lead in drinking water is 15 parts per billion (source: EPA Lead and Copper Rule) — far lower than the levels tested in the lab.
What This Means for Tea Drinkers
If you’re already a daily tea drinker, this study is simply a fascinating bonus: your tea habit could be giving you a tiny extra layer of protection against harmful metals.
Here’s how to potentially enhance the effect:
- Choose loose-leaf or cellulose tea bags over nylon or cotton.
- Brew for longer — a few extra minutes could mean more contaminants are adsorbed.
- Drink a variety of teas — black tea may be slightly more effective, but all teas tested had some benefits.
- Don’t rely on tea as a filter — for real water safety, use a certified water filtration system if you suspect contamination.
A Word of Caution
While this research is promising, it’s not a substitute for safe water infrastructure. In cases of significant water contamination, proper filtration or alternative water sources are essential. Tea should be seen as a complementary benefit, not a primary solution.
Tea has been consumed for thousands of years for its flavor, aroma, and health benefits. Now, science has revealed yet another surprising property: a natural ability to capture and hold heavy metals from water. While it won’t replace a Brita filter anytime soon, it’s a comforting thought that your favorite brew might be working behind the scenes to make your cup just a little cleaner.
