CDPH Lead Inspector/Assessor California State Practice Exam

What is the main cause of lead contamination in drinking water?

1. Lead pipes being used

2. Corrosion of lead-containing materials in plumbing

3. Contaminated well water

4. Lead-based paint runoff

The correct answer is: Corrosion of lead-containing materials in plumbing

The primary cause of lead contamination in drinking water is the corrosion of lead-containing materials in plumbing. Many older homes and buildings were constructed with plumbing systems that included lead pipes, solder, or fixtures which could leach lead into the water supply, particularly when the water is acidic or has low mineral content. Over time, the surfaces of these materials can deteriorate, leading to the release of lead particles into the drinking water. This process of corrosion is exacerbated by factors such as water temperature, pH levels, and the presence of certain chemicals in the water, which can increase the likelihood of lead leaching. As a result, even if lead pipes themselves are not present, any lead solder or fixtures still in use can contribute to lead contamination due to the corrosion process. Understanding this mechanism is crucial for preventing lead exposure and ensuring safe drinking water.