Which heavy metal is known to cause poisoning when present in drinking water?

Lead is recognized as a significant contaminant that can lead to poisoning when present in drinking water. This heavy metal poses serious health risks, particularly to vulnerable populations such as children and pregnant women. Exposure to lead can occur through various sources, including lead pipes, plumbing fixtures, and solder used in water systems. As lead leaches into the water supply, it can lead to various health problems, including developmental issues in children, cognitive impairments, and various neurological effects.

Unlike lead, copper and zinc can also cause health issues but typically only at higher concentrations and are regulated in drinking water standards to prevent acute problems. Iron, while essential in small amounts, can give rise to aesthetic concerns such as staining and unpleasant taste but is generally not considered toxic in drinking water at concentrations that typically occur. Therefore, lead stands out as the heavy metal specifically associated with poisoning in drinking water.