What phenomenon is likely to occur if two dissimilar metals are connected in plumbing?

When two dissimilar metals are connected in plumbing, the phenomenon that is likely to occur is corrosion, specifically galvanic corrosion. This occurs because different metals have different electrode potentials, which can lead to an electrochemical reaction when they are in contact with each other and in the presence of an electrolyte (like water).

In this scenario, one metal (the anode) will corrode faster than the other (the cathode). The less noble metal, or the one that is more anodic, will experience deterioration as it loses electrons, while the more noble metal remains relatively unharmed. This can lead to significant damage in plumbing systems over time, as leaks and failures may arise from the weakened structure of the corroded pipe or fitting.

While the other options like freeze damage, scaling, and clogging relate to water systems in different ways—such as temperature changes affecting pipe integrity, mineral buildup causing flow obstructions, and debris accumulation causing blockages—they do not directly result from the connection of dissimilar metals. Therefore, corrosion is the phenomenon that is most pertinent in this context.