One thing that can happen to a buildings drainage system is backflow. This usually occurs when mud, soil, or loose leaves have made their way into your drainage pipes clogging the system altogether. Clogs are typically quick and relatively painless to deal with and usually only need a day for repairs to be made. One danger that can happen is backflow can cause your drainage system to rupture, causing water and other liquids to leak under the foundation of the building. If this occurs, more extensive repairs may be needed, such as concrete repairs or releveling of the foundation.