Which type of pipes is not recommended for conveying water for human consumption due to toxicity?

Lead pipes are not recommended for conveying water for human consumption due to their toxicity. Lead is a heavy metal that can leach into the water supply, particularly in conditions where the water is slightly acidic or has low mineral content. The presence of lead in drinking water is a significant health risk, as it can accumulate in the body over time and lead to serious health issues, particularly affecting the nervous system, brain development in children, and overall organ function.

In contrast, copper pipes are generally considered safe for plumbing systems if installed and maintained properly, as copper does not leach harmful levels into drinking water under normal conditions. Clay pipes, primarily used in drainage and sewage systems, do not pose toxicity concerns for drinking water. Bituminous pipes, which are more commonly associated with drainage and non-potable applications, also do not have the same health concerns as lead. Therefore, lead pipes are the clear choice when discussing materials that are inappropriate for conveying drinking water.