Which of the following is NOT a common material used in older plumbing systems that could contain lead?

Polyethylene pipes are not a common material associated with lead in older plumbing systems. In fact, polyethylene is a type of plastic that has been used primarily in more modern plumbing applications due to its resistance to corrosion and its non-toxic nature, making it a safer choice for drinking water systems.

On the other hand, lead pipes, brass fittings, and solder are all materials historically used in plumbing systems that may contain lead. Lead pipes were commonly installed before the dangers of lead exposure were fully understood. Brass fittings often have some percentage of lead incorporated into their alloy, especially in older fittings. Similarly, lead-based solder was frequently used in the joining of pipes, adding to the potential lead exposure in existing plumbing systems. This knowledge is crucial for understanding the risks of lead contamination in drinking water and the importance of replacing these materials for public health and safety.