It has become common scenes in Toronto when it rains: pedestrians jumping across puddles and cars traveling through pools of water.

Toronto, as a young city, is always proud of its energy and dynamics. Yet, the city’s aging sewer system tells a different story. From the first day of 2010 to the end of this February, Toronto’s 311 received more than 20.5 thousand service requests in regard to a flood situation, meaning that the city has to deal with at least 6 flood complaints each day.


This analysis is based on the city’s 311 open data though not a reflection of the whole picture. The city disclaims that the data is a glance of all city-wide services and it takes up only 30 percent to 35 percent of all contacts. Therefore, this analysis, though solely shows results from published data, can indicate similar trends.

In the duration of nearly 10 years, there are 17 days when the city is flooded with more than a hundred of calls requesting flood services. The three days in February 2014 put a particularly challenging test on the city’s response to flooding as over a thousand requesting such a service.

Because of influx calls in February and a significant increase of rainfalls in June and October, the year of 2014 has the largest amount of flood complaints. The number of this year (2019), with only two months of calls being counted, is already higher than the total of 2010 and close to that of 2016.


In general, the total number of flooding complaints is correlated with precipitation. A wetter year clearly sees more complaints. Whenever there is a large increase in rainfall, there will be a spike of 311 incoming calls. During the rainy seasons, the changes occur almost simultaneously. Whereas in winter or early spring, more 311 calls come a few days after the snowfall as warm temperatures start to melt snows.

How frequent Torontonians deal with flood problems also depends on where they live.

Unsurprisingly, complaints rise in areas that are close to bodies of water: people living alongside Don River and Humber River registered more flooding complaints than their counterparts from other parts of the city.

Neighborhoods in the south of Eglinton Ave. and along the east side of the Humber River made the most flooding complaints to 311.

Some intersections also have a higher tendency to be submerged underwater after heavy rainfalls. Here are the top 10 intersections for street flooding complaints:

  • Dundas St W & Jane St
  • Jane St & St Clair Ave W
  • Bloor St E & Parliament St
  • Parkside Dr. & Bloor St W
  • Bloor St W & St George St
  • Bloor St E & Castle Frank Rd
  • The Queensway & Parkside Dr.
  • Don Mills Rd & York Mills Rd
  • Wynford Dr. Eglinton W Ramp & Eglinton E Wynford Dr. Ramp
  • Royal York S Dundas E Ramp & Royal York N Dundas W Ramp
  • Madelaine Ave & Danforth Ave



Technical notes: the data for this analysis can be obtained from Toronto’s open data portal. To view the detailed analysis with annotation and code for the interactive features, please go to my Github page.

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