Why Sewers Around the World Keep Overflowing

TL;DR

Sewage overflows, resulting from combined sewer systems, are increasing due to climate change and urbanization, causing pollution and health issues in lakes and rivers.

Transcript

Hi, this is David from MinuteEarth. In early May of 2019, the Chicago sewer system ejected over a million gallons of a slurry of poop and toxic chemicals into the Chicago River and out into Lake Michigan. Needless to say, this wasn’t great for the creatures that live in the lake, or the people who live by the lake - aka the citizens of Chicago. And... Read More

Key Insights

• 💨 Combined sewer systems were initially a convenient way to remove waste but caused sewage overflows when storms overwhelmed processing plants.
• 💱 Climate change-induced megastorms and urbanization increase the frequency and severity of combined sewer overflows.
• 🤝 Separating storm runoff from sewage or diverting runoff into waterways are potential solutions for cities dealing with sewage overflows.
• 💖 Green infrastructure, such as parks and roof gardens, can help absorb stormwater and prevent it from overwhelming the sewer systems.
• 🏙️ Retrofitting existing cities with separate sewer systems is costly and impractical.
• 🥺 Sewage overflows contaminate water supplies, leading to pollution, illness, and the death of aquatic life.
• 🚨 The installation of overflow tanks, like Chicago's 10 billion-gallon tank, can provide temporary relief during sewer emergencies.

Questions & Answers

Q: Why did cities install combined sewer systems?

Combined sewer systems were installed to easily remove different types of waste, combining sewage and storm runoff. It reduced the need for separate systems.

Q: What causes sewage overflows in combined sewer systems?

Megastorms, intensified by climate change, overwhelm the processing plant capacity, leading to raw sewage overflow into nearby waterways.

Q: Is there a solution for the sewage overflow problem in existing cities?

Retrofitting existing cities with separate sewer systems is expensive and inconvenient. Other solutions include diverting storm runoff, building parks and roof gardens to absorb rainwater, and constructing overflow tanks.

Q: How do combined sewer systems contribute to pollution?

Combined sewer overflows release untreated sewage, which contains toxic chemicals and pathogens, polluting water supplies, harming plants and animals, and causing beach closures and health issues.

Summary & Key Takeaways

• Cities like Chicago installed combined sewer systems in the late 1800s to remove various waste types, but it led to sewage overflow into waterways.

• With the addition of processing plants, the sewage overflows were reduced, but megastorms caused by climate change overload the capacity and lead to contamination.

• To combat sewer overflows, cities can separate storm runoff from sewage or divert runoff into nearby waterways. Parks and roof gardens are also being used to absorb stormwater.