Canada dumps billions of litres of raw sewage into natural waterways annually. How can we stop?

This story is part of Uytae Lee’s Stories About Here, an original series with the…

This story is part of Uytae Lee’s Stories About Here, an original series with the CBC Creator Network. You can watch every episode of this series on CBC Gem.

Last summer, three Metro Vancouver beaches were closed to swimmers after high levels of E. coli were detected in the water.

And this is a pretty common occurrence. Almost every year, beaches, lakes, and other water bodies are closed to swimming across Canada because there is fecal matter mixed into the water. Our poop!

So how did that poop get there?

Well, it’s because of something called the combined sewer and stormwater system.

Mixing sewage with stormwater

When you flush your stuff, it flows into a network of sewage pipes that lead to a sewage treatment plant where it is cleaned and treated before the remaining water is dumped into the ocean.

Pretty straightforward right? 

But in a combined sewer and stormwater system, sewage isn’t the only thing that goes into those pipes. There’s also stormwater.

In a combined sewer and stormwater system, city infrastructure can quickly become overwhelmed during major rainfall events. (Stories About Here)

In a combined system, rain that hits a hard surface like asphalt, glass or concrete also flows into our sewage system to be cleaned and treated.

And this is where we find the root of this problem: The amount of sewage flowing in a city at any given time is pretty consistent, but the amount of rainwater a city receives fluctuates wildly. So when there’s a bad rainstorm, there ends up being far too much water flowing through our pipes for the sewage treatment plant to handle.

The result? All the excess stormwater and sewage overflows into a nearby body of water, whether it’s a stream, lake, or beach. 

Grey and green infrastructure

This combined system has historically been the system of choice for most older cities in North America, which means this is a problem pretty much everywhere. 

In 2017, over 167 billion litres of combined sewage and stormwater leaked into water bodies across Canada, in every province except for P.E.I., Newfoundland, and Saskatchewan.

So how do we stop doing that?

Well, there are many different solutions and they roughly fall into two categories: Grey infrastructure and green infrastructure.

“Grey Infrastructure” is a more heavy-duty approach to dealing with excess stormwater. One example is in Tokyo, where the city has constructed enormous underground caves to hold excess liquid during typhoon season.

Another popular solution is to completely separate stormwater and sewage into different pipe networks, so sewage can be taken to sewage treatment plants, while stormwater can just flow out into the ocean.

But these solutions are incredibly complicated, expensive and don’t always work. And that’s where green infrastructure comes in.

The process of separating pipes in Vancouver into separate stormwater and sewage systems has been ongoing since the 1970s and will take years to complete. (Stories About Here/City of Vancouver)

Easier being green?

Out in the wild, there are no pipes. When it rains, water is absorbed into the ground or pooled into streams and rivers that flow into lakes and oceans.

“Green infrastructure” is what happens when cities try to mimic that process in an urban area. This includes making green roofs or other permeable spaces that collect and absorb rainwater. It can even be as simple as planting more trees, which are very good at soaking up water.

But this approach isn’t perfect, either. Green infrastructure doesn’t make sense everywhere and the science behind it is admittedly less predictable than simply directing water into a pipe.

What I’ve really come to understand is it will take many different solutions working together to manage our sewage and stormwater. 

And I do have hope, that if we keep our eyes on the prize, one day, maybe — just maybe — we’ll finally stop dumping literal sewage into the ocean.

Learn more in Stories About Here: How to Stop Dumping Sewage into the Water

About this series

Stories About Here is an original series with the CBC Creator Network that explores the urban planning challenges that communities across Canada face today. In each episode we dig into the often overlooked issues in our own backyards — whether it’s the shortage of public bathrooms, sewage leaking into the water, or the bureaucratic roots of the housing crisis. Through it all, we hope to inspire people to become better informed and engaged members of their communities.

You can watch every episode of this series on CBC Gem.