One of the City of Cornwall's largest responsibilities involves the collection and treatment of wastewater. This is accomplished through an extensive sewer network and a primary Wastewater Treatment Plant and pumping station on Montreal Road in the east end of the City.

The City of Cornwall strives to maintain high standards in wastewater treatment to ensure there is minimum effect on the St. Lawrence River.

Located at 2800 Montreal Road, the City of Cornwall Wastewater Treatment Plant was originally built in 1968, and the facility has undergone several expansions since that time. The treatment plant has undergone a $55.5-million upgrade resulting in the addition of secondary treatment and an increase in capacity. 

The existing plant currently serves approximately 46,000 residents as well as numerous commercial and industrial customers. It has an average rated capacity of 54,000 cubic metres per day and a peak design capacity of 108,000 cubic metres per day.

Sewage from the City of Cornwall is collected and transferred by gravity to a pumping station on the south side of Montreal Road, near the entrance to the Wastewater Treatment Plant.

The sewage passes through a screen at the pumping station before being pumped through a forcemain to the treatment plant, where grit is removed in aerated grit tanks. After degritting, the sewage is transferred to four clarifiers where it is disinfected using chlorine. The treated effluent is then discharged into the St. Lawrence River.

Solids that settle in the clarifiers are pumped to two digesters where organic matter is decomposed and methane is generated. This methane is used as a fuel for building heat. The decomposed organic matter is removed from the digesters, dewatered in centrifuges and landfilled for final disposal.


Protect our Wastewater Treatment Plant!

Just because the items you flush leave the toilet bowl, doesn't mean they have made it through the sewer system - or even left your building! Flushing some items can cause major issues in your building, community, and environment. Even if something says it's "flushable", this doesn't mean it's good for your toilet, your plumbing, or our environment.



  • pee
  • poop
  • toilet paper
Keep it simple and only flush the three p's: pee, poop, and (toilet) paper.
litter, feminine hygiene product, cotton swab

Do not flush:

  • kitty litter
  • feminine hygiene products
  • cotton swabs and pads
These items do not break down - they can actually clump together and cause clogs.
chemicals, medication, cigarette

Do not flush:

  • cleaning products
  • medication
  • cigarettes

These items can contaminate the water system.
They can poison aquatic environments, infiltrate drinking water, kill good bacteria, and increase bacterial resistance to pharmaceuticals.

flushable wipes and kleenex

Do not flush:

  • paper towels
  • tissues
  • "flushable" wipes
  • baby wipes
These items are too thick and sturdy to flush. They do not break down and can build up, causing clogs.
bandaid, floss

Do not flush:

  • bandaids
  • floss
  • gum
  • condoms

These items are not biodegradable. They will stick together, stick to other items, and stick to the
inside of your pipes, creating

phone icon Contact Us