Most of the time, the City's sewer pipes have adequate capacity to carry wastewater to the treatment plant. But during heavy, extended raining periods when the ground water is high, the capacity of some sections of the sewer system is exceeded. Ground water or surface water will enter older sewer pipes through cracks and, added to the wastewater flow, will exceed the space available in the pipe. When these conditions occur the water has to go somewhere. If it can't flow down the main pipe, it will back up into the service line and, possibly, all the way into the basement.
