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Wastewater education, reporting and statistics

Disposing of fats, oils and grease

Did you know that nearly half of the sewer pipe blockages in Ottawa are caused by the accumulation of fats, oils and grease?

How do fats, oils and grease cause sewer backups?

When liquid fats, oils and grease are washed down the sink or toilet, these materials solidify and stick to the inside of your plumbing or to city sewer pipes. This can result in a blockage and lead to sewer backups. 

Where do fats, oils, and grease come from?

Most fats, oils and grease are a result of cooking, and can be found in meats, fats, lards, cooking oil, shortening, butter and margarine, salad dressings, and dairy products.

What can you do to help prevent sewer backups?

  • NEVER pour fats, oils or grease down sink drains or toilets.
  • DO NOT use hot water or chemicals to flush grease down the drain.
  • DO NOT install or use a food grinder in your kitchen sink.
  • ALWAYS place strainers into sink drains to catch food scraps.
  • For restaurant owners the installation of a grease interceptor is mandatory, and is regulated under Sewer Use By-law 2003 - 514.

Tips on how to properly dispose of fat, oil and grease

  • Let grease cool and harden, then scrape it from trays, plates, pots and pans, and grills into your green bin.
  • Pour liquid cooking oil or any liquid food waste into a biodegradable container (such as a milk carton) and place into your green bin.
  • Absorb all liquid fats, oils, or grease with paper towels and place the soiled paper towels into your green bin.
  • Not sure how to dispose of an item or substance? Use our Waste Explorer to find out.
  • Green Bin your Grease!

For more information, please contact a representative of the Sewer Use Program at 613-580-2424 ext. 23326.

Pool and hot tub maintenance

Pool and hot tub water contains chemicals – commonly chlorine/bromine, salt, copper-based algaecides, and more - that are harmful to fish and aquatic life. Practicing proper pool and hot tub maintenance will help protect and preserve Ottawa's aquatic habitats.

To practice responsible maintenance for swimming pools and hot tubs, it is important to be aware of the difference between storm sewers and sanitary sewers.

Below are two examples of storm sewers, which lead directly into the City's waterways:

Storm sewer grate, with fish icon.   A storm sewer

Stormwater is not treated at the City’s wastewater treatment plant. Discharging pool chemicals to a storm sewer kills the naturally occurring bacteria necessary to aquatic life in creeks, rivers, and streams.

How do I prepare my pool for the end of the season?

  • Two weeks before draining, stop adding chemicals to your pool or hot tub to allow time for the chemicals to dissipate.
  • After the two weeks all pools and hot tubs can be discharged onto your property, provided the water can be properly absorbed into the ground, so as not to migrate onto a neighbour’s property. To protect your home and neighbouring properties, be sure to consider the slope and surface of your property, along with the discharge flow rate.
  • Due to the high level of chlorides, salt water pools are prohibited from being discharged to the storm sewer, per the Sewer Use By-law. Salt water pools must be carefully discharged to the sanitary sewer connection located on your property or hauled away by a licensed hauler.
  • Filter backwash water must be discharged to the sanitary sewer or discharged onto your property, if it can be properly absorbed into the ground. Due to harmful chemicals and debris, backwash is prohibited from being discharged to the storm sewer. 

Your responsibility

A pool or hot tub owner is responsible for safely maintaining and operating these amenities. If your pool water has entered a stream, river, lake or storm sewer system without proper treatment, you and your pool service provider are legally obligated to report the discharge to the Ministry of the Environment - Spills Action Centre (1-800-268-6060) and the City of Ottawa (3-1-1).

The City’s responsibility

The City’s responsibility is to protect the environment. Where necessary, the City will intervene to enforce environmental protection in accordance with the Sewer Use By-law.

For more information on the City’s Sewer Use By-law, contact a representative of the Sewer Use Program at 613-580-2424 ext. 23326.

What NOT to flush down the toilet

Your toilet is not a green bin or a garbage can. Flushing certain items can result in a back-up of the sewer line into your home or can create problems at the City's wastewater treatment plant.

Only flush the three Ps – pee, poo and toilet paper! These are the only items that belong in your toilet.

The following items should never be flushed down the toilet:

  • Personal care wipes/baby wipes
  • Diapers
  • Cotton swabs
  • Hair
  • Dental floss
  • Tampons
  • Sanitary products
  • Condoms
  • Old medicines
  • Grease/fat from food

How can I dispose of these items?

Visit the Waste Explorer to find out how to dispose of these items.

Why shouldn't "flushable" wipes be flushed down the toilet?

While products may be advertised as "flushable," in reality items such as baby wipes, makeup remover cloths, and disinfectant wipes do not decompose in the sanitary sewer system. Flushing this material causes damage to the sewer system and may cause sewer backups in your home. Flushables should be disposed of in the garbage.

Wastewater: Frequently asked questions

Answers to the most commonly asked questions about wastewater. If you have a question that is not addressed, please call 3-1-1.

Wastewater collection

Why is the storm drain in front of my home not draining faster when it rains?

Sometimes, it seems the catch basins are not handling enough water to drain the street properly. This can be caused by debris such as leaves or grass clippings obstructing the grate. Your help in keeping the grates free of debris is valued and appreciated.

If the catch basin grate is clear and clean but does not drain quickly enough during heavy rainstorms, it may not mean the storm system is not functioning. During heavy rainstorms, the short term storage of rainwater on the streets is one of the means to avoid overwhelming the storm water collection system and the means to avoid the possibility of flooding basements. It is much better to have water on the street for a short duration than to have sewer backups. To prevent sewer backups, the City has restricted the catch basin capacity to match the capacity of the pipes.

Where does rain water go?

The City of Ottawa has three types of sewers: sanitary, storm and combined.

Sanitary sewers collect wastewater from homes, businesses and industrial sites, and transport the waste water through a network of sewers, pumping stations and forcemains to trunk sewers which direct flow to the Robert O. Pickard Environmental Centre for treatment before being discharged to the Ottawa River.

Storm sewers carry rainfall and other surface water run-off directly to the nearest creek, stream or river, generally without treatment.

Combined sewers collect and transport a mixture of both sanitary and storm water in a single pipe. Combined sewers only exist in a very small area of the City. Geographically most of the City is serviced by separated sewers. Most of this flow is transported to treatment plants, but when the 2.4m diameter pipe collecting the combined sewage is flowing at full capacity, the excess overflows to the river to prevent sewer backups into basements. This legacy system was designed and built when 100% of the city sewage was flowing directly to the Ottawa River. Today, 99.7% of sewage is fully treated. 

The frequency and duration of the overflows within a combined sewer system depends on the volume of precipitation in a particular area and the sewer characteristics of the area. Some combined sewers rarely overflow, while others overflow when it rains.

What is a combined sewer overflow?

Learn more about combined sewer overflows.

What is the City doing to reduce spills to the Ottawa River?

Learn what the City is doing to reduce spills to the Ottawa River.

How do I properly discharge my pool water?

Learn maintenance tips for swimming pools and hot tubs.

How do I dispose of RV waste?

The Robert O. Pickard Environmental Centre (ROPEC) accepts waste from recreational vehicles (RV) such as trailers, camper vans, and motor homes. This service is free of charge. Please present yourself at the front gate:

800 Green Creek Drive, Monday to Friday between 8:00 a.m. and 2:30 p.m. (closed on statutory holidays).

You will be directed to wait in a designated area until City staff becomes available to escort you to the discharge location and assist you. Water for flushing your tank will not be provided on site. Closed toed shoes and work gloves are recommended while on-site. Please note, general information will be requested in order to complete a log sheet for tracking purposes.

Why shouldn't "flushable" wipes be flushed down the toilet?

While products may be advertised as "flushable," in reality items such as baby wipes, makeup remover cloths, and disinfectant wipes do not decompose in the sanitary sewer system. Flushing this material causes damage to the sewer system and may cause sewer backups in your home. Flushables should be disposed of in the garbage.

Wastewater treatment

What is wastewater?

Wastewater is water that has been used and discharged by homes, businesses and industries. Domestic wastewater includes typical wastes from the kitchen, bathroom and laundry. Wastewater is thoroughly treated at the Robert O. Pickard Environmental Centre to ensure it is safe for the public’s health and the environment.

How does the wastewater treatment plant work?

Find out how the City treats wastewater at the Robert O. Pickard Environmental Centre (ROPEC).

What does it cost to treat wastewater?

Find out what it costs to treat wastewater.

Sewer backups and flooding

What do I do if my sewer backs up?

Learn what to do if your sewer backs up.

How do I apply for the Residential Protective Plumbing Grants program? 

The City offers assistance to eligible homeowners to cover the cost of installing protective plumbing devices. For more information, consult information on the Residential Protective Plumbing Program.

What is a blow-back and why do they happen?

Learn about blow-backs and why they happen.

Educational materials

Let’s Explore Wastewater Treatment (brochure)

Download a printable version of the wastewater treatment process brochure.

Wastewater Treatment Plant - Robert O. Pickard Environmental Center

The Robert O. Pickard Environmental Centre (ROPEC) is located in the city's east end, right next to the Ottawa River. Using an extensive sewer system, all of the wastewater is collected from homes and businesses between Stittsville, Orleans and Manotick.

Whenever we use water, we contaminate it - whether we flush the toilet, take a shower, wash dishes, or do the laundry.  All of this water can be easily treated at ROPEC.  Other materials are more difficult to break down or remove, such as deodorants and some hair care products.

Substances like oil or paint are not meant to be treated by a municipal sewage plant. For information on how to properly dispose of hazardous waste, check out the Waste Explorer.

Ottawa's wastewater treatment plant:

  • Cleans an average of 390 million litres of wastewater every day - enough to fill more than 6,000 backyard swimming pools
  • Protects the environment.  When the water is returned to the Ottawa River, its levels of bacteria, phosphorus and organics are far below all limits set by the plant's operating permit.  The E.coli count, for example, reaches only 14 per cent of the allowed amount.
  • Produces 39 dry tonnes of biosolids each day, which are used as agricultural fertilizer

The Wastewater Treatment Process

1.  Coarse Screening/Pumping

Wastewater flows to the plant through enormous pipes buried deep in the ground. Upon arrival, any object bigger than a shoe gets screened out. The sewage is then pumped to ground level. It flows through the rest of the treatment processes by gravity.

2.  Fine Screening/Degrit

Screens catch smaller objects like sticks and rags. Degrit tanks separate pebbles, grit and sand from the other solids that can be further treated. Screenings and grit are trucked to a landfill and buried.

3.  Primary Clarification

The plant has 15 covered settling tanks. Water is slowed down to allow heavy solids to sink to the bottom, while grease and fat float to the surface. The settled solids (sludge) and floatables (scum) are removed by skimmers and sent to digesters (step 9). The remaining water still contains very fine solids and dissolved material like sugar.

4.  Aeration

In these long and deep uncovered tanks, naturally occurring bacteria break down the small particles. Air is blown into the tanks, making bubbles. This creates ideal conditions for the bacteria and keeps the solids from settling.

5.  Phosphorus Removal

A solution of iron is added to the wastewater. Iron captures the phosphorus, creating a solid that can sink and be separated from the water.

6.  Secondary Clarification

16 round open tanks slow the wastewater down, allowing the remaining solids and bacteria to settle as sludge. Most of the sludge is continuously pumped back to the aeration tanks, so that the bacteria can biodegrade more waste. Excess sludge is further processed (step 9).

7.  Disinfection

Leaving the secondary clarifier, the water is disinfected by adding chlorine, the equivalent of strong household bleach. This kills the majority of microorganisms that have survived the treatment process.

8.  Dechlorination

A final chemical is added to remove excess chlorine. Now the treated water can be returned to the river.

9.  Biosolids Processing

Excess sludge and scum is treated in six sealed tanks (anaerobic digesters), using other naturally occurring bacteria. These bacteria convert about half of the sludge into methane gas, and carbon dioxide. The rest goes through centrifuges, where water is removed.  What is left is a nutrient-rich, soil-like material called biosolids. Farmers use it as a fertilizer.

10.  Cogeneration

The methane gas that has been produced in the anaerobic digesters is burned in engines and boilers, producing heat and electricity that is used to run the plant.

Cease the Grease

Download a printable version of the brochure.

Hauled liquid waste from rural restaurants can be a problem for Ottawa's wastewater treatment plant.  You can be the solution.

The City's wastewater treatment plant is designed to treat sewage from various sources.  To be accepted at the Robert O. Pickard Environmental Centre (ROPEC), all wastewater must meet the limits set by the Sewer Use By-law (2003-514).

Liquid waste that is brought in from rural restaurants can cause problems at ROPEC.  If a grease trap is absent or not properly maintained, the oils and fats can clog the plant's piping and equipment.  The grease has to be manually removed at a high cost.

Commercial hauled liquid waste is classified as 'restricted waste'. Restricted waste will not be discharged at ROPEC unless it has been approved by City staff, prior to being picked up by a licensed hauler.  Restricted waste is received at ROPEC Monday to Friday from 8 a.m. to 3 p.m., excluding statutory holidays.

Rural restaurants, food trucks, caterers and other food service establishments can request an exemption from the restricted waste category - if they can provide proof of a grease trap and maintenance records.  Once exempted, staff will determine if the hauled liquid waste may be mixed with domestic sewage which is accepted between 7 a.m. and midnight, seven days a week.

These don't go down the drain...

  • Cooking oil
  • Lard
  • Shortening
  • Melted butter
  • Meat fats
  • Creamy sauces
  • Batter
  • Gravy

This keeps grease out of your wastewater...

  • Install a grease trap if you don't have one. It's a provincial law.
  • Check and clean your grease trap regularly and properly.
  • Recycle used oil.
  • Scrape all remaining food from plates and utensils before washing them.
  • Always use sink basket strainers to collect food waste.
  • Train your staff.
  • Used a licensed hauler

Sinks Are Not Garbage Cans - Restaurant Grease (brochure)

Download a printable version of the brochure.

Keep grease out of the sewer

Restaurants, food-service operations and establishments are major contributors to grease accumulation in our sewers, and the resulting blockages and backups.  Major sources of grease are baking goods, lard, food scraps, cooking oil, shortening, butter, creamy sauces, dairy products (i.e. milkshakes), meat fats, batter and gravy.

What is a grease trap?

Grease traps and interceptors are containment units that are designed to trap grease, oil, solids and other debris.  They prevent these substances from getting into the sanitary sewer systems where they can accumulate and eventually block the entire pipe.

Grease traps and inceptors need to be properly sized, installed and, most importantly, maintained!

What to do with grease?

When cleaning the grease trap or interceptor scoop out the solidified grease portion on the top and place in the grease recycling bin or garbage for disposal.  Place the liquid portion in a sealable container.  Used cooking oil can be recycled. Storage bins can be obtained from cooking oil recyclers, usually at no cost.  There are several companies that are certified and licensed grease removal contractors.

Keeping a logbook of all cleanouts and maintenance, either by you or a contractor will help maintain a grease trap / interceptor cleaning schedule.

What you should do?

  • Place screens over drains
  • Wipe grease from dishes and pots
  • Recycle used oil
  • Train employees
  • Scrape food scraps and grease into green bin or garbage
  • Check grease trap often and clean often
  • Don’t pour grease down drains or toilets
  • Don’t use degreasers, emulsifiers or hot water to dissolve grease
  • Avoid pouring grease straight into garbage dumpster

Did you know?

  • Grease build-up is the main cause of restaurant sewer backups
  • Restaurant sewer backup may result in immediate closure
  • Grease build-up can flood basements throughout the city
  • Grease trap installation and maintenance is Mandatory
  • Don’t use emulsifiers, degreasers, or hot water to clean grease
  • Employee education is the key to success

Why is it important to you?

Under the Ontario Building Code 350.06, grease traps are required anywhere food is cooked, processed or prepared.  There are also enforceable limits in Ottawa’s Sewer Use By-law that prohibit the discharge of grease and oil over certain levels.  These limits are enforceable through penalties and fines.

It is very expensive to return the sewer back to normal after a grease blockage and backup.  This cost by the City can be charged back to the restaurant or food establishment.  If a blockage does occur, the Public Health inspector may close the restaurant, and any restaurant upstream of the blockage, until water use can resume.  This could result in an entire day or more of lost operating hours and revenue.

Grease build-up in the sewer system and treatment facility results in higher operating costs, which can result in higher sewer rates and taxes for Ottawa residents.

These don’t go down the drain:

  • Cooking oil
  • Butter
  • Gravy
  • Meat fats
  • Sauces

All About Sewers (activity book)

Learn more about Ottawa's sewers through fun games and puzzles in our downloadable activity book!