Retubing a concrete wall fountain involves replacing the worn-out or damaged tubes that carry water through the fountain. It requires the use of specialized tools, such as a tube cutter and a flare tool, as well as materials like copper tubing and fittings. The process typically involves cutting the old tubes, flaring the ends of the new tubes, and connecting them using compression fittings or solder. Retubing ensures that water flows smoothly and prevents leaks, maintaining the aesthetic appeal and function of the fountain.