Sanitary sewer overflows, otherwise known as SSOs, are a major cause for concern in many residences, buildings and communities.

Sanitary sewer overflows can be defined as raw sewage that seeps from municipal, industrial or residential sanitary systems. Sanitary systems are responsible for transporting sewage collected by domestic, commercial and industrial buildings to facilities for treatment. When these systems malfunction, the raw sewage that escapes can cause major problems to the surrounding environment and can have adverse effects on people that come in contact with it.

According to the EPA, or Environmental Protection Agency, there are an estimated 23,000-75,000 sanitary sewer outbreaks in the United States, alone. This number does not include back ups that occur into industrial buildings and residences. These outbreaks can affect city streets, playground equipment, parks, streams and much more.

As of yet, the Environmental Protection Agency has devised a committee designed to help tackle many of the concerns surrounding sanitary sewer overflows across the nation. The committee, known as the Federal Advisory Subcommittee, is composed of municipalities, health agents, state representatives, and advocacy groups to address the varying needs of every city with regard to SSOs.

The needs of every city often differ wildly, and as such, require a specified plan of action that may look different from one community to the next. Some of the needs that the Federal Advisory Subcommittee seeks to address include:

  • Defining maintenance principles
  • Notifying the public of sewer overflows
  • Managing public policy issues
  • Communicating health implications of sewage overflows with the public
  • Effective sewer operation techniques

Causes of Sewer Overflows

As previously mentioned, sanitary sewer systems are designed to collect city, residential and industrial sewage and contain it, until it can reach a treatment facility. Unfortunately, there are many times when these systems malfunction, causing a whirlwind of challenges, health implications and safety issues to arise that threaten homes, businesses and communities. Thus, it is important to understand why sanitary sewer systems overflow.

Inflow and Infiltration: Sometimes, sewage pipes that are leaky, broken or faulty may experience an influx of water that comes from other sources, that eventually inundates the pipes and causes them to overflow. This influx of water can often be the result of thawing snow in the spring, excess rainfall, roof drains and more.

Lack of Capacity: There are times when a community is expanding or new subdivisions are established throughout a city. Though exciting for community members, the expansion of commercial and industrial structures can wreak havoc on sewage systems that may be too small to handle the increased volume of sewage that the new developments bring. As a result, these overwhelmed sanitary sewage systems may overflow, causing sewer water to back up.

Aging, Broken or Corroded Pipes: A common issue in all building types, aging, broken or corroded pipes can spell trouble when it comes to sewer backups. With their fragile and otherwise compromised functionality, these weakened sewer systems are especially vulnerable to collapsing or breaking, which, in turn, will interfere with the ability of sewage to flow through.

Blocked Pipes: In addition to aging or corroded piping comes the common issue of sediment build-up and objects that can become lodged in sewer systems. The buildup can happen over time, or can evolve quickly, depending on the issue. Regardless, this is an easy and very common way, in which sewer systems fail to function properly resulting in sewage overflow.

Faulty or Improperly Installed Pipes: Sometimes, the issue with the ongoing malfunctioning of sewer systems have to do with how they were installed in the first place. Without proper installation, or with a lack of proper maintenance, sewer systems will, understandably, lose their effectiveness over time. The result will be numerous backups that pose multiple risks to affected communities and their inhabitants.

Varying Communities Yield Varying Needs

Although the aforementioned reasons for sanitary sewer overflows are common, it should be noted that various communities experience overflows for varying reasons and to varying degrees. As a result, the needs of one community will likely differ greatly from the needs of another.

Nevertheless, a sample of six communities revealed that the most common cause of sanitary sewer overflows was that of pipe blockages, at 43%. Infiltration and inflow proved to be another common issue, affecting nearly 27% of the sewer systems analyzed in the study. Of the other reported causes, 12% of SSOs were the result of broken pipes, 11% of power failure and 7% were the result of insufficient sanitary system capacity.


To conclude, sanitary sewage overflows, or SSOs, are an issue plaguing many cities, industries, communities and residences. Steps toward remediating this problem have been pursued by municipalities all over. The Environmental Protection Agency has sought to address this problem with the formation of the Federal Advisory Subcommittee, who works to ensure that the needs of all cities and communities are addressed in regards to the problematic nature of sewer overflows.

Though the plan of action required to address SSOs in each community tends to flex based on the need, it is important that the public remains aware and is educated on the dangers of SSOs, so as to better protect themselves, and other, from harm as cities and communities work to identify and address these issues at their source.