Advanced water treatment systems, such as reverse osmosis and other water treatment technologies, are deployed in industrialized nations to counter the threat posed by arsenic in drinking water. As these systems are largely unavailable in underdeveloped regions due to cost and lack of infrastructure, researchers from the City University of New York sought to brew up a more economical solution for arsenic remediation.

The researchers engineered teabags that target arsenic in water. The devices are composed of cellulose, embedded with magnetic iron oxide nanoparticles, and filled with pulverized eggshells, low-cost materials with excellent adsorptive capacities for arsenic ions. This dual-component design capitalizes on the strong affinity between arsenic species and both iron oxides and calcium carbonate — the primary constituent of eggshells — to effectively capture and remove the contaminant from water.

These specialized teabags aren’t for making tea — they are an inexpensive and effective way to remove arsenic from drinking water. Source: ACS Omega 2026, DOI: 10.1021/acsomega.5c12885

The system described in ACS Omega is inexpensive, costing around 7 cents to clean a liter of water, and highly effective, removing over 90% of the arsenic ions present. In a sample representative of well water in Bangladesh, one teabag reduced the arsenic content to below the World Health Organization’s a safe drinking water limit of 10 micrograms of arsenic per liter.

Users simply immerse the teabag into contaminated water, allowing it to adsorb arsenic ions over time. It is designed to be reusable; after use, the teabag can be rinsed in an alkaline solution, dried, and reused up to five times.