You can prevent condensation on a cold-water line in hot weather by using:

Using insulation on a cold-water line in hot weather effectively prevents condensation. When warm, humid air comes into contact with the cold surface of the pipe, moisture is likely to condense on it, leading to dripping and water damage. Insulation acts as a barrier, keeping the cold water line from being in direct contact with the warm air. This reduces the temperature differential that causes condensation, thus minimizing or eliminating the formation of moisture on the pipe's surface.

Insulation materials, such as foam or fiberglass, are specifically designed to resist heat, making them ideal for this situation. They help maintain the temperature of the water in the pipes and reduce the risk of condensation. In addition to preventing potential damage, proper insulation also contributes to energy efficiency by reducing heat transfer in both hot and cold pipes.