Which of the following materials is FDA approved for contact use in potable systems?

The correct answer is FDA approved plastic because it specifically denotes materials that have been verified and certified by the FDA for safe use in contact with potable (drinking) water systems. The FDA sets rigorous standards for materials used in food and beverage contact applications, ensuring they do not leach harmful chemicals into the liquids they come into contact with.

FDA approved plastics are designed to meet these stringent safety requirements, making them suitable for applications in potable water systems where consumer safety is paramount. This certification provides assurance that the material is tested and compliant with health and safety standards.

Silicone rubber, while often used in various applications including some food contact, doesn't have universal FDA approval for all types. Not all PVC is FDA approved, and its suitability can depend on specific formulations and additives used in each case. Steel alloys can be used in potable water systems, but they must also meet certain standards for corrosion resistance and safety, and may not have the same level of direct FDA approval as specifically designated plastics do.

Thus, FDA approved plastic is the most appropriate choice when considering materials for direct contact with potable water systems.