City of Knoxville
Engineering Department
Stormwater Engineering Division

Sanitary sewer overflows (SSOs) are a violation of NPDES permits that are issued by Tennessee Department of Environment and Conservation (TDEC).

What is an SSO?

A sanitary sewer overflow (SSO) is raw untreated sewage that discharges from the sanitary sewer system without first passing through a wastewater treatment plant. A typical SSO may occur at a manhole during wet weather, but can also occur in dry weather for a variety of reasons. An SSO is a public health hazard and a violation of federal, state and local discharge regulations.

Typical signs of an SSO include:

Displaced manhole lids

Oftentimes, the SSO discharge may not look or smell unusual. The toilet paper may have been "filtered" within the sewer pipe or somewhere upstream. Or the discharge may be diluted by groundwater or surface water infiltration.

How you can learn more:

PDF Files

EPA - Raw Sewage Enforcement Alert

Benefits of Protecting Your Community From SSOs

Sanitary Sewer Overflows (EPA 832-K-96-001)

EPA Web Site: Overview of Sanitary Sewer Overflows

EPA Web Site: Why Control Sanitary Sewer Overflows

What you should do: