Wastewater management in Guelph

Wastewater 101

What you drain or flush affects everyone along the wastewater path: your family, next-door neighbour, 131,000-plus Guelph residents and even the friendly fish enjoying a swim in the Speed River. What goes down comes around.

  • Putting something down the drain? Can you cool, scrape and toss it instead?
  • Flushing something? Only if it’s one of the three Ps: pee, poo or (toilet) paper.
  • Pouring something onto the street? Only rain and snowmelt can go into storm drains.

What goes down comes around

Stormwater isn’t processed through Guelph’s Water Resource Recovery Centre. It flows directly into the Speed River. That’s why it’s so important to prevent harmful substances from car washing from flowing into the storm drains on your street. Instead head to a commercial car wash. They capture harmful substances like motor oils and greases before sending the water down the sewer for treatment.

Every shower we take, every load of laundry we wash and every toilet we flush all feed into the infrastructure we share beyond the pipes in our own homes – from the sewage system that runs under our streets to the Water Resource Recovery Centre that cleans our water.

Protecting Guelph’s water

Water is a finite resource and it’s our collective responsibility to save and protect it.

What is wastewater?

Any water you flush down your toilet or drainpipes is wastewater. After leaving your home, the wastewater flows into a single big/main pipe, which also collects wastewater from thousands of other households in your community. This is where clogs most commonly happen, and when they do, they can back up the sewage system for entire neighbourhoods.

Gravity then moves the wastewater through the main pipe towards the City of Guelph’s Water Resource Recovery Centre (sometimes with a little extra boost from a pumping station).

The City processes and treats the equivalent of 208 million glasses of water every day!

What causes clogs?

Clogs are most often caused by fats, oils and greases. While they may make our food much tastier, they can also stick to the inside of pipes. There, they can build up over time, adding to other items that have been incorrectly flushed or drained.

Fatbergs, caused by a collection of wipes and other debris and “sealed” together with Fats, Oils and Greases, can reach sizes of 40 tonnes and measure the size of a double-decker bus… imagine that under Wyndham Street!

Items that cause clogs include:

  • Food scraps, everything from the crust off a peanut butter sandwich to morning coffee grounds can cause a blockage in pipes or accumulate along with other debris, fats, oils and greases.
  • Medication may help us live longer, healthier lives, but they have the opposite impact on our environment if they’re poured down a drain or flushed down a toilet. Even award-winning wastewater treatment facilities like ours can’t remove these chemicals.
  • ‘Flushable’ wipes aren’t actually flushable; they get stuck in pipes because they aren’t designed to break apart like toilet paper. They’re a leading culprit behind damage to wastewater systems around the world.
  • Paper towels, tissues and napkins are similar to wipes and don’t break down inside of pipes quickly enough to avoid clogging.
  • Menstrual products and diapers aren’t designed to break down like toilet paper (in fact, they’re designed to absorb liquid and expand).
  • Household chemicals, include things like cleaners, polishes, disinfectants and de-greasers, cannot be removed from wastewater through treatment.
  • Paint can cause build-ups and leach dangerous chemicals into our water system that can’t be removed during the treatment process.
  • Chemically treated pool/hot tub water: Drain it into your home’s tub or sink or let it gradually drain onto your lawn or garden and be filtered by nature.

When we avoid flushing or draining items that don’t belong in our sewer systems, we collectively reduce wear and tear on our pumps, pipes and treatment facilities. Equipment lasts longer and we don’t need to spend time or resources de-clogging pipes and pumps.

Not sure how to dispose of something? If it can’t go down the drain, it has to go somewhere else. Check out the Waste Wizard to figure out where to put your waste!

When water reaches the treatment facility – what happens?

When wastewater arrives at the City’s Water Resource Recovery Centre, it flows through a screen that separates out larger debris such as toy cars, cellphones and diamond rings. These items are trucked off to landfill.

The remaining water then takes a two-and-a-half-hour rest in a large settling tank where smaller bits of debris or sludge (grit, sand and dirt) settle to the bottom, while fats, oils and greases, called ‘scum’, rise to the top. We don’t want either in our water system, so we skim the top and dredge the bottom.

To reduce the impact on the environment, we take these by-products and feed them to microorganisms that turn them into biosolids that are used to make fertilizer. This process also creates methane gas, which we capture and use to generate heat and electricity for the wastewater plant.

The wastewater then makes its way over to an aeration tank where we add air, creating a paradise for oxygen-loving microorganisms that munch on any remaining organic waste over seven hours.

From there, the water moves to a tank where the microorganisms settle to the bottom. We collect them for later and send them back to the aeration tank. Any particles that are left in the water at this point are removed by passing through a sand filter.

Finally, we add a small amount of chlorine to the water to kill any harmful bacteria or germs and finally remove the chlorine—which is harmful to fish, plants and wildlife—before pumping the treated water into the Speed River.

What about the sludge and scum?

As for all that sludge and scum removed during the settling process, we pump that to our digesters. The digesters work like stomachs; anaerobic microorganisms that live in the digester consume bacteria and help reduce pathogens and odours to produce biosolids.

As the microorganisms consume bacteria, they create methane gas. We capture and use the methane to generate heat and electricity to help power the wastewater plant—enough energy to power 1,975 houses.

When the microorganisms consume most of the bacteria, we separate excess water from the biosolids and treat them using heat, alkali, and high shear mixing. Then the material is available for agricultural purposes, sod farming, golf courses, horticulture, forestry, reclamation and bioremediation.

Latest updates

No recent news, check back later!

Annual reports

Related resources

For more information

Monday to Friday 8 a.m. to 4 p.m.
[email protected]
519-837-5629

Report a spill

Please tell us about your experience. Take this survey to help us continue improving City services.