Cobalt is a metal found in rocks and used in industry. It can enter water from mining and manufacturing. Excessive exposure may cause thyroid and heart problems.

Cobalt naturally occurs in rocks and soil, but its presence in water often stems from human activities. Industrial processes, including the production of alloys, batteries, and pigments, can release cobalt into the environment. It enters water sources through mining operations, manufacturing runoff, and natural erosion of cobalt-containing minerals. Environmental agencies typically measure cobalt levels in water using atomic absorption spectroscopy. While essential in trace amounts for vitamin B12 formation, excessive cobalt exposure is a concern for public health.