If sewage is backing up, keep people away from the affected area and call before the problem spreads. Water Main Canada helps you move from panic to a clear sequence: stop use, inspect the likely source, and get the right technician moving.
In Hamilton, local conditions matter. Mention Hamilton's combined sewer overflow risks, local municipal sewer authority contact, typical winter freeze/thaw issues for ON. That does not mean every property has the same problem, but it does mean the inspection should consider weather, pipe age, ground movement, municipal connection points, and the way water is behaving inside the building.
The goal is to protect the property first, then choose the least disruptive repair path that actually solves the problem. Call 1-888-702-2090 if the situation is active or you are unsure whether it can wait.