International Compliance Association (ICA) Home Inspector Practice Exam

What generally causes pinhole leaks in brass service pipes?

1. Corrosion from air exposure

2. Leaching zinc

3. Temperature fluctuations

4. Chemical reactions with water

The correct answer is: Leaching zinc

Pinhole leaks in brass service pipes are primarily caused by the leaching of zinc. Brass is an alloy composed mainly of copper and zinc. Over time, especially in certain water conditions, the zinc can leach out of the brass, leading to a loss of structural integrity within the pipe. This leaching occurs more rapidly in environments with high levels of dissolved oxygen or varying water chemistry, which can create conditions conducive to preferential corrosion of the zinc component. When zinc is leached from the alloy, it can leave behind small holes or pinholes in the brass, as the copper remains but the zinc, which offers protection and stability, diminishes. As a result, the area becomes more susceptible to corrosion and ultimately develops leaks. Understanding this process highlights the importance of monitoring water quality and the conditions in which brass piping is used. If the water's chemistry is not balanced properly, it can accelerate the leaching process, leading to more frequent issues with leaks in brass plumbing systems.