Rania Hamza calls it “a coincidence” that an engineer, a biologist and a lawyer at the same Toronto university were independently worrying about the harmful substances and chemicals being flushed down Ontario’s toilets. Three years ago, after figuring out they were all interested in the same thing, the unlikely trio came together to highlight a major gap in policy.

The release of everyday wastewater from our homes and businesses into the environment is Canada’s largest source of water pollution. This dirty water is full of toxic substances that can harm our lakes and rivers. Some is removed or treated, like the phosphorus in sewage that creates harmful algae blooms in water. But many more unmonitored and invisible substances — or “contaminants of emerging concern” — in wastewater end up being dumped into the Great Lakes, which hold around 20 per cent of the world’s surface freshwater and about 85 per cent of North America’s.

In Canada, no rule or law to prevent emerging contaminants from entering our water — something Hamza and her colleagues want to change.