Sanitary Sewer Overflows & Infiltration/Inflow

A sanitary sewer overflow (SSO) is an event in which untreated sewage is discharged from a sanitary sewer into the environment prior to reaching sewage treatment facilities, generally caused by too much rainwater or snow/ice melt. An SSO can spill raw sewage into home basements or out of manholes and into city streets, playgrounds, and waterways.

Infiltration and inflow (I/I) occurs when excess water flows into sewer pipes from groundwater and stormwater. Groundwater (infiltration) seeps into sewer pipes through holes, cracks, joint failures, and faulty connections. Excess water can enter sewer pipes through roof drains and broken or badly connected sewer service lines (inflow).

To learn more about the hazards of aging infrastructure see What Can We Learn from Jackson? Mississippi’s Water Crisis is an Infrastructure Wake-up Call Part 1 and Part 2.

Sewer System Management

The Environmental Protection Agency (EPA) has found that SSOs caused by poor sewer collection system management poses substantial health and environmental challenges. Because SSOs contain raw sewage, they can carry bacteria, viruses, parasitic organisms, molds, fungi, and more. The diseases they can cause range in severity from mild to life-threatening (see examples below). Exposure to pathogens can occur through sewage in drinking water sources, direct contact in areas of high public access, or in waters used for recreation.

The need to upgrade Greenville County’s deteriorating sewer system, which includes pipes that are more than 100 years old, was a major factor driving the unification of the county’s separate sewer collection systems. Unification helps to ensure that sewers are properly installed and maintained, and helps to avoid widespread problems that over time could be expensive to fix. The CWF initiative will help reduce SSOs and I/I, improve water quality, mitigate health risks, keep costs down for ratepayers, and help ensure public safety.

Common Pathogens & Diseases/Symptoms Associated with SSOs