Beryllium is a metal used in aerospace and electronics. It can enter water through industrial discharge. Inhaling beryllium dust causes serious lung damage.

Beryllium occurs naturally in rocks and soil, but industrial activities increase its presence in water. It's used in nuclear reactors, X-ray machines, and alloys. Beryllium can enter water through mining runoff, industrial discharges, and erosion of deposits. It's typically measured in parts per billion using atomic absorption spectroscopy. While inhalation risks are well-known, ingestion through water may cause intestinal lesions. The EPA has set a maximum contaminant level of 4 ppb in drinking water to protect public health.