Frequently Asked Questions: Sanitary Sewer Overflows (SSOs)

What are collection systems? 

Collection systems transport sewage, or untreated wastewater, to wastewater treatment facilities through sewer lines and force mains, which are sewer lines that carry wastewater under pressure from pumps or lift stations. In North Carolina, collection systems are regulated under 15A NCAC02T.

What is a sanitary sewer overflow?

Sanitary Sewer overflows, or SSOs, are discharges of untreated wastewater from collection systems. If the discharge reaches waters of the state or waters of the U.S., they are considered prohibited point source discharges unless authorized by a National Pollutant Discharge Elimination System (NPDES) permit.

Why do sanitary sewer overflows occur?

Potential causes of overflows can include line breaks or failure of other equipment, often from pump stations; inflow and infiltration of water into the system, especially during heavy rains; aging infrastructure; vandalism; and blockages caused by debris or vegetation.

In addition, blockages can be caused by discharges of fats, oils and grease, sometimes known as “FOG,” into the collection system, or the flushing of household products such as nonwoven wipes, including baby wipes or facial wipes.

What are some of the risks from SSOs for human health or the environment?

Generally, excessive nutrients, like nitrogen or phosphorus, from treated or untreated wastewater spills can help stimulate the growth of algae, deplete dissolved oxygen in the water that support fish and other organisms and can contribute harmful bacteria or pathogens. Depending on concentration in the receiving stream, a spill could also cause vegetation to die off or kill fish.

The N.C. Department of Health and Human Services has information about water-borne illnesses online. DHHS advises the public to take precautions to protect yourself and others against water-borne illnesses when swimming or playing in or on the water.

Can SSOs be prevented?

Members of the public can call DEQ staff to report an active sanitary sewer overflow. Please see the information in the next section below for contact information.

In addition, the public can play a role in preventing SSOs by following protocols for disposal of household waste. Non-flushable items, including non-woven wipes, should be disposed of in the trash. Read online about the role home kitchens and restaurants can play in proper disposal of fats, oils and grease to prevent discharges into sanitary sewer systems.  

DWR’s collection system permits include sections for performance standards, operation and maintenance, inspections, record keeping and general conditions. Systems are encouraged to be proactive and preventive in operations and maintenance. Their permits also require them to have prevention and response plans in place for sanitary sewer overflows. 

SSOs can be linked to aging infrastructure. DEQ is working to provide systems with funding through the Division of Water Infrastructure to address these issues.

To track reported sanitary sewer overflows, or to check to see if one has already been reported, use the Division of Water Resource’s SSO tracking tool online: NC DWR Sanitary Sewer Overflow Reports. 

How do I report an SSO?

To track reported sanitary sewer overflows, or to check to see if one has already been reported for your area, use the Division of Water Resource’s SSO tracking tool online: NC DWR Sanitary Sewer Overflow Reports. The general public can use this tool to get more information about an SSO event, as well as the potential response.

If you are reporting an SSO or another active environmental situation, contacting the nearest DEQ Regional Office allows staff to respond and investigate more effectively. If you prefer not to report a complaint or concern directly to our regional office staff, you may submit your comment or complaint via NCDEQ’s Anonymous Comment Tool, which can be used to provide anonymous suggestions or complaints about an environmental concern or an incident of discrimination involving an environmental concern.