Manganese in groundwater poses risk to 200 million people globally, study reveals

On July 8, 2026, a study published by Eawag—Swiss Federal Institute of Aquatic Science and Technology—revealed that approximately 200 million people worldwide are at risk of consuming drinking water contaminated with manganese. The research highlights significant concerns in densely populated regions of Asia and along the Mississippi River in the USA.

Manganese Contamination: A Global Issue

Manganese is an essential trace element necessary for human health, but excessive concentrations can lead to severe health issues. The study estimates that between 180 million and 220 million people are drinking water with manganese levels exceeding the World Health Organization (WHO) guideline of 80 micrograms per liter. Alarmingly, 90% of those affected reside in Asia.

The research team, led by environmental scientist Joel Podgorski and geochemist Michael Berg, compiled nearly 300,000 groundwater measurements from various sources to create a global risk map. This map identifies high-risk areas based on environmental factors such as climate, geology, and soil properties.

Health Risks Associated with Manganese

While manganese is vital in small amounts, excessive exposure can damage the nervous system, particularly in infants and children. The WHO had previously adjusted its guideline value for manganese in drinking water from 400 to 80 micrograms per liter in 2021. In contrast, Switzerland and the EU have set even stricter limits, capping it at 50 micrograms per liter.

Identifying High-Risk Areas

The study indicates that large river deltas and young sedimentary landscapes are particularly vulnerable to manganese contamination. Key hotspots include:

• Ganges-Brahmaputra Delta in Bangladesh and India
• Mekong Delta
• Red River Delta near Hanoi
• Parts of Pakistan
• Mississippi River in the USA

According to the researchers, the geological conditions in these areas facilitate the accumulation of manganese in groundwater due to geochemical processes. However, areas in Europe and particularly Switzerland show lower risk levels, as most populations rely on treated water sources.

As groundwater containing manganese comes into contact with oxygen, it can be effectively treated using simple treatment methods, which can help mitigate the risks associated with manganese contamination.