From the Tampa Bay Times:

The recent sewage discharge into Tampa Bay was a result of the excessive rainfall, but only indirectly. The primary and more compelling reason is a sanitary sewer system that is in disrepair. A properly functioning sanitary sewer system will not be adversely affected by rainfall. (Stormwater sewer systems operate separately.) The fact that rainfall increases the volumes at water treatment plants indicates that the system is allowing infiltration. Infiltration is groundwater or rainfall seeping into the sanitary sewer system. This is a problem that can be fixed by having sanitary sewer lines and manholes repaired or replaced. If the existing system is repaired and/or replaced, it would allow the existing water treatment plants to just treat sewage as they were designed, and not treat rainwater.

Continue reading