Once we’ve flushed our toilet, washed the dishes, or turned off the shower, we rarely think about exactly where it is that the water you’ve just used goes. Taking advantage of the advanced infrastructure running underneath our city is both a privilege and a right. However, understanding the importance of Toronto sewer repair and proper water treatment means that you’re contributing to a healthy water infrastructure system.

After deadly cholera outbreaks were reported due to the exposure to sewage in the 1800’s, the City of Toronto began investing in water mains to carry the city’s wastewater. While central plumbing was introduced in 1880, Toronto’s largest treatment plan, The Ashbridges Bay Treatment Plant wasn’t built until 1910.

Laying underground wastewater and sewage lines

By 1953, there were 18 wastewater treatment plants throughout the Greater Toronto Area, which were then converted to wastewater pumping stations by 1960 to direct all wastewater to the four big treatment plants.

Toronto’s treatment plants:

Since we pull our drinking water from Lake Ontario, every ounce of water and waste that you wash down the sink and flush down the toilet needs to be treated before it ends up back in Lake Ontario. The cycle of cleaning, using, and disposing of water is never ending, and there are four main water treatment plants within the city limits of Toronto.

Toronto’s water mains are all diverted to one of these four treatment plants in order to thoroughly clean and dispose of waste water.

Ashbridges Bay
Built in 1910, the Ashbridges Bay Wastewater Treatment Plant is both the first and the largest treatment plant in Toronto. The treatment plant features

  • A capacity of 818,000 m3/day
  • Serves a population of 1,524,000
  • Cost $56.4M to run in 2015

Accepting excess untreated wastewater from the North Toronto treatment plant, Ashbridges Bay is also home to Ashbridges Bay Park which features marinas, biking trails, picnic sites, and is a regular spot for special event fireworks.

Highland Creek
Located in Scarborough, the Highland Creek Wastewater Treatment plant was completed in 1956.

  • Capacity of 219,000 m3/day
  • Serves population of 509,000
  • Operational costs for 2015 equal $18.7

Humber River
Serving the western edge of the City of Toronto, the Humber River Wastewater Treatment Plant was completed in 1960.

  • Capacity of 473,000 m3/day
  • Serves population of 685,000
  • Operational costs for 2015 equal $17.1M

North Toronto
Serving the northern edge of Toronto, the North Toronto Wastewater Treatment Plant was one of the first plants in North America to use the biological activated sludge process that breaks down organic matter to separate liquids from solids.

  • Capacity of 40 ML/day
  • Serves a population of 55,000
  • Excess waste is diverted to Ashbridges Bay via Coxwell sanitary trunk sewer
  • Operational costs for 2015 equal $1.70M

Inside the sewer images: http://www.vanishingpoint.ca/sewers

If you add up the populations served by our wastewater treatment plants, it comes to 2.78 million. However, the population of Toronto as of 2015 was 2.79 million and growing. Reducing waste; purchasing low flow toilets, showerheads, and faucets; and practicing practical sewer main repair in Toronto means can take the strain off of these plants.

How it’s Processed:

Your wastewater goes through five stages of treatment before being released back into Lake Ontario.

  1. Preliminary treatment to eliminate big objects such as sticks, rocks, and debris while slowing down the flow to encourage sand and grit to sink to the bottom of the tank.
  2. Separating solids from liquids in the settling tank by letting everything sit for several hours.
  3. Biological treatment to remove small bits from the wastewater by encouraging micro-organisms to eat very small bits of organic waste.
  4. Finally, before being released into the lake, the wastewater is treated with chlorine to remove harmful pathogens.
  5. Both the primary solids and secondary solids are send to the digester where micro-organisms spend 15 days converting the waste to methane gas.
  6. Any additional biosolids are sent to the landfill, the incinerator, or used as fertilizer.


Thanks to the high standards that our wastewater is treated, the waste that once ended up in Lake Ontario is treated and removed. This means that our lakes  and beaches are safer for swimming and fishing.

As of 2015 data, 9 out of 11 of Toronto’s beaches are safe for swimming, out of which eight are considered blue flag beaches that achieve high standards in 33 criteria. According to Environmental Defence, despite runoff and excess untreated water, the beaches exceed national water quality standards for 91% of the summer season.

How can Toronto sewer repair affect wastewater treatment?

Toronto has an average of 1100 water main breaks per year, this means that wastewater that was being properly diverted is now potentially running directly back into the nearest waterway. Through drain cleaning in Toronto, and Toronto water main maintenance, you can do your part to ensure that our wastewater ends up where it should be — treated — before being released back into nature.

If you have an ageing Toronto water main, or sewer that is clogged, backed up, or broken, the trained pipelining technicians at Aquazen Services can make sure that your problem is resolved and your water is flowing as normal. Give us a call today to discuss an inspection of your Toronto water main.


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