Researchers at Northwestern University have discovered that tea leaves can naturally filter out heavy metals like lead and cadmium from drinking water. The study found that the type of tea, brewing method, and steeping time all play a role in adsorbing contaminants.
According to senior author Vinayak P. Dravid, the goal of the study was to measure tea’s ability to absorb heavy metals. The researchers created water solutions with known amounts of lead and other metals, then added tea leaves and measured how much metal content remained in the water after steeping.
The results showed that the type of bag used can affect the effectiveness of the filter. Cellulose bags worked best, while cotton and nylon bags absorbed very little of the contaminants. The researchers also found that longer steeping times resulted in more metal being adsorbed.
While tea leaves are not a substitute for traditional water filters, the study suggests that brewing tea could contribute to reduced heavy metal exposure worldwide. The researchers estimate that tea preparation can remove up to 15% of lead from drinking water, even at high concentrations.
The study’s findings have implications for public health research and could potentially explain why populations with higher tea consumption rates may have lower incidence rates of heart disease and stroke.
Source: https://news.northwestern.edu/stories/2025/02/brewing-tea-removes-lead-from-water