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Sanitary Sewer Overflows

Sanitary Sewer Overflows

EPA estimates that there are at least 40,000 sewer system overflows each year.  In South Carolina, over the last 10 years, an average of almost 600 overflows have been reported each year.  The untreated sewage from these overflows can contaminate our waters, causing serious water quality problems. Sewage can also back up into basements, causing property damage and threatening public health.

Sewer systems are meant to collect and transport all of the sewage that flows into them to a wastewater treatment facility.  When a discharge of raw sewage occurs from the sewage collection system, it’s called a sewer system overflow or SSO.  Wastewater overflows happen for a variety of reasons.  Some occur during dry weather due to blockages in the system, vandalism, construction activities, pipe failures, pumping failures, grease accumulation, root intrusion into sewer lines, a lack of proper maintenance and a myriad of other reasons.  Other overflows occur during wet weather when inflow and infiltration into sewer lines overwhelms the sewer system.  Utilities which own and operate sewer collection systems must report overflows to the Department.  As a general rule, utilities are only required to formally report overflows of 500 gallons or more.  This is intended to accommodate small releases due to maintenance activities or other causes which should not pose a threat to public health or the environment.  However, some utilities elect to report all overflows, including those which are below 500 gallons.

Not all collection systems flow directly to a treatment facility.  Some are collection systems only and discharge to sewer systems owned by another entity.  These are called Satellite Sewer Systems.  For more information about these systems, go to the following

Satellite Sewer System page

So that DHEC will have accurate information about the person responsible for each satellite sewer system in the state, the following form must be completed.

Satellite Sewer System Owner Notification Form

Since 1998, SCDHEC has required the reporting of SSOs for any overflow that reaches waters of the state, for overflows that exceed an estimated 500 gallons that don’t reach water, and for any overflow that may cause a public health or environmental concern.

Collection system operators that need to report Sewer System Overflows, use the
following form:

Sewer System Overflow or Pump Station Failure Report Form

In 2008, SCDHEC initiated a voluntary public notification program.  Public and private utilities were asked to develop a program to notify the public whenever they had an SSO exceeding an estimated 5,000 gallons.  Many utilities, including a lot of the major public utilities chose to participate, however, a number chose not to develop a notification program.  SCDHEC has committed to providing notification when a utility does not.

View Wastewater Overflows

The volumes reported are estimates and are assumed to be the net volume lost to the environment.  Utilities sometimes are able to recover portions of the total SSO and may not report the recovered volume.

For More Information Contact

  • SCDHEC Columbia, Bureau of Water, Compliance Manager
    Brian Wisnewski at (803) 898-4160

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