Do I need to replace leaking basement windows? 

Not all leaking basement windows necessarily need to be replaced. The necessity for replacement depends on the severity of the leak, the condition of the window, and the underlying cause of the leak. In some cases, repairs and improvements such as sealing gaps, improving drainage, and installing vapor barriers may resolve the issue. However, if the window is severely damaged, aged, or the material has decayed significantly, replacement might be the most effective long-term solution.