All persons installing polyethylene piping must be __________.

Individuals installing polyethylene piping must be trained to ensure they possess the necessary knowledge and skills to perform the installation safely and correctly. This training includes understanding the properties of polyethylene, the proper handling techniques, installation methods, and adherence to safety protocols in accordance with local regulations and industry standards.

Being trained helps to mitigate risks such as leaks or structural failures, which can lead to safety hazards and environmental concerns. Training also ensures that installers are familiar with the specific requirements for working with polyethylene as opposed to other materials, as the handling and installation techniques can vary significantly.

While licensing, certification, and supervision might also be applicable in certain contexts, the primary requirement emphasized here is the need for training to ensure competence in the specific task of installing polyethylene piping effectively and safely.