Beneath Toronto, even under its “underground city,” lies 11 kilometres of tunnels and pipes, some over 200 years old. This is Toronto’s sewer system—a crucial element of urban life. Ready to uncover Toronto’s subterranean mystery? Let’s dive into its history. Learn more at toronto.name.
General Information About Toronto’s Sewer System
Every major city has an extensive waste disposal system, and Toronto is no exception. Its sewer system comprises 11 kilometres of tunnels (roughly four metres per resident). This engineering marvel allows Torontonians to dispose of waste effortlessly. The system evolved over decades through the integration of smaller systems into a centralized network, ensuring the city’s high sanitation standards for centuries to come.
Some of the original systems were simpler than others. Toronto’s unique network of ravines necessitated high-capacity storm drains to manage heavy rainfall effectively. These drains now form some of the least complex parts of the modern sewer system. However, the sections added during the city’s major expansions are more intricate. Designed to service new areas, they separate sanitary sewage (“dirty waste”) from surface runoff (“stormwater”). The oldest parts of the system, dating back to the 1800s, are particularly fascinating. These consist of narrow, egg-shaped brick tunnels, sometimes barely wide enough to navigate, sloping steeply to allow gravity to transport waste to its destination.
Strain on Toronto’s Sewer System
Many older systems were built around natural waterways, which once carried waste before the expanding city buried them. Toronto’s “lost rivers,” such as Rosedale Creek and Lavender Creek, still exist today as combined sewer segments, handling both human waste and stormwater.
Toronto occasionally experiences heavy rainfall—so much so that its historic areas have faced flooding risks for over a century. Even today, the city battles sewer overflows and the contamination of Lake Ontario. Advanced facilities, storage reservoirs, and intercepting mains have been added beneath city streets to ensure waste is appropriately managed. During extreme rain, excess water from combined sewers is diverted to massive concrete reservoirs, where it remains until it can be treated. However, maintaining this system is a constant challenge, as extreme weather and population growth demand ongoing upgrades.
Exploring Toronto’s Sewers: Disease Potential
Modern Toronto has increased storage facilities and added pumping stations (84 as of 2024). Despite these improvements, most residents remain unaware of the perpetual battle waged beneath their feet. Like any old, hidden infrastructure, Toronto’s sewer system attracts urban explorers. The hazards—dangerous gases, sudden water surges, and risks of disease or infection—seem to intrigue rather than deter. However, unauthorized exploration is highly discouraged. Visits require permission from municipal authorities, and there are excellent online resources to experience Toronto’s tunnels and underground systems virtually.
Toronto’s Sewer System in the 19th Century
Understanding Toronto’s sewer system as it was in 1870 sheds light on its impact on urban sanitation and health. Sewers weren’t automatically installed with new streets. Most homes relied on private backyard pits, which were either manually emptied or connected to street drainage pipes. Drainage often flowed into streams or rivers unless linked to one of several trunk sewers that discharged eastward into the Don River or southward into Lake Ontario.
Implementing sewer systems was a complex process dating back to 1859. Residents seeking sewer services had to petition the city council, securing signatures from at least two-thirds of property owners whose properties represented at least half the assessed value of the affected area. Once a petition was approved, an inspector determined the properties impacted and calculated each household’s share of the costs. The tax was based on the property’s value, improvements, frontage, and the benefits derived from the sewer.
Theoretically, the council could install sewers without residents’ consent, but they couldn’t force residents to pay for them. As a result, sewer projects were usually undertaken only when residents initiated them. By 1879, the city had expanded outward, introducing new streets within its old boundaries. During this period, many streets, particularly in the northeast, received new sewers through petitions.
Since 1848, the Board of Works—a permanent committee of aldermen and municipal officers—oversaw sewer construction and public works tasks assigned by the Board of Health, such as street cleaning, watering, and waste removal. By 1870, the Board of Works and Board of Health operated closely following their merger in 1869. This cost-saving measure didn’t grant the Board of Works new health-related responsibilities but drew criticism from urban reformers advocating for higher environmental standards.
In the late 19th century, Canadian urban reformers embraced the “sanitary idea” that emerged in England during the 1830s and 1840s. Reformers in Toronto recognized the connection between environmental quality and citizens’ physical and moral health. This belief in environmental morality was shaped by progressive germ theory, which linked diseases to specific microbes.
These reforms significantly influenced Toronto’s sewer system development. The 19th-century debates over sanitation underscored the importance of clean water and efficient waste disposal, paving the way for modern sewer infrastructure that continues to evolve today.