The interesting parts of this article from the Toronto star about recent flooding are these:
“There is nothing we can do to prevent this from happening a couple of times a year,” and
One of the less costly implementations Drake suggested is a stormwater utility charge, which increases a water bill based on how much stormwater a property generates that the city has to then manage.
https://www.ctvnews.ca/canada/toronto-s-density-old-sewer-system-lead-to-issues-with-flooding-1.4062372