Sewers and wastewater

The City of London currently manages five wastewater treatment plants and 38 pumping stations. Keeping London's pipes free and clear helps reduce back ups, basement flooding, and environmental impacts. 

REport a sewer-related issue

Get a Fats Oils and Grease (FOG) Cup

Free FOG Cups can be picked up at City of London EnviroDepots and at London Public Library locations.  

What is FOG and why do we collect it?

Fats, oils, and grease (FOG) can block London's sewer system when they're poured down your sink or into your toilet.  When FOG hardens, you could end up flooding your basement or even your neighbour's.

The City of London provides residents free FOG Cups to collect their fats, oils, and grease. When the cup is full, it can be returned to a City of London EnviroDepot where it will be used to generate green energy. 

One full FOG Cup can be turned into enough energy to power a refrigerator for a day. 

The degradable FOG cup can also be placed in your garbage. If you do not have a FOG cup, you can also collect fats, oils, and grease in a coffee cup or can that you can place in the freezer. When it is full, please throw it out in your garbage.

Please use a City of London FOG cup if you hope to return it to an EnviroDepot to be converted into green energy. 

If you have questions about FOG cups or this program, please contact Barry Orr at or call 519-661-2489 x 6306

Best practices for residents and businesses

Toilets and sinks are not garbage cans

Drains are designed for wastewater and toilet paper only. Flushing the wrong things down your toilet or sink can block sewer pipes and may cause flooding at your home.  It is also extremely important to keep medicines and garbage out of the toilet.

This includes:

  • Wipes
    • Do not flush any type of wipe, even if they say on the packaging they are flushable 
  • Medicine
    • Remember to always dispose of medicines by taking them to your pharmacy
  • Face masks

Only rain should go down the drain

Storm sewers and catchbasins collect water outside and drain directly into the nearest creek, river or lake. This water is not treated, so it is important to not put waste such as animal waste, automotive fluids, garbage, and chemicals down a catchbasin.

Pouring any chemicals in the storm sewer is illegal and pollutes our rivers and lakes.

One litre of motor oil spilled down a catchbasin can contaminate one million litres of water.

When you wash your car on your driveway or the street, the soapy, dirty water runs into our creeks and river. To avoid having dirty water run into our storm sewer system, consider these options for washing your car:

  • Use a commercial car wash facility. These facilities treat wastewater and discharge it into the sanitary sewer system where it will receive further treatment. Commercial car washes are regulated to practice water conservation. Washing your car at home can use as much as 50 percent more water.
  • Find a location where the wastewater won’t flow into the storm sewer. For example, washing cars on a gravel surface or grass allows the wastewater to be absorbed before it reaches the storm sewer.

Draining pools and hot tubs

If you are draining a pool or hot tub, remember to dechlorinate the water and drain onto your lawn, if it can be properly absorbed into the ground without flowing onto your neighbours property or storm water system.

Salt water pools should be discharged to the sanitary system connection on your property. The water from salt water pools have such high levels of chlorides that this water cannot be discharged to the storm sewer system.

Restaurant grease

Grease build up is often the main cause of sewer back ups at restaurants.  Grease interceptors are required anywhere food is cooked, processed or prepared. 

Grease interceptors are containment units designed to trap grease, oil, solids and other debris. They prevent these substances from getting into the sanitary sewer system where they can eventually block the entire pipe. Grease interceptors need to be properly sized, installed and maintained. Cleaning food wastes and oil out of grease interceptors is required on a regular basis.  

Oil and grit separators

Oil and grit separators are structures  integrated into the City’s stormwater system. As rain and melted snow wash from the ground surface and enter stormwater grates located on roads and in parking lots, oil and grit separators:

  • Remove sediment
  • Screen debris
  • Separate oil 

Property and business owners are responsible for maintaining this device as per London’s Waste Discharge By-law. Spills happen, so make sure your oil and grit separator is working properly to capture them.

If an oil and grit separator is not maintained, it can result in toxic runoff entering our stormwater system

Construction sites

Erosion and sediment control plans are an integral part of site development and construction sites.  Sanitary sewers are not built to handle storm water from construction sites and basements.

It is also important to manage wash water at a construction site.  Wash water for latex paint or concrete should never go into the storm sewer system. 

For more information and educational materials, please contact Wastewater Treatment Operations at 519-661-5701

Overflows and bypasses

A sewer system overflow occurs when sanitary sewers are overwhelmed by stormwater inflow during wet weather events. 

A wastewater treatment plant bypass occurs when flow exceeds capacity of the treatment plant. Untreated wastewater and storm water discharge directly into local waterways through an outlet to assist in preventing basement flooding. The wastewater treatment plant treats as much sewage as possible prior to any plant bypass by directing a portion of the flow to receive primary treatment but it bypasses secondary treatment.

To reduce overflow and bypass issues reduction of weeping tile drains to the sanitary sewer is required. It is estimated that there are approximately 50,000 homes within the City of London that have weeping tiles directly connected to the sanitary sewer.  These flows can overwhelm the sewer system during heavy rainfall and can cause basement flooding, sewer system overflows, and bypasses. 

To request information about overflow and bypass data, please contact Wastewater Treatment Operations at 519-661-5701

How can you help?

If your home's weeping tile is connected to the sanitary sewer inside your home, you can have your weeping tiles disconnected from the sanitary sewer and reconnected to the City’s stormwater system.

The City has the Basement Flooding Grant Program in place to assist homeowners with the cost.

For further questions about the Basement Flooding Grant By-law, or to find out if you qualify for grant program, please contact Kelly Christensen at or call 519-661-2489 x 4696

Combined sewers

In some cases, both sanitary and stormwater drain into a common pipeline that leads it to a nearby wastewater treatment plant. This type of sewer is no longer constructed, but is occasionally found in old sewer systems. 

The City of London has invested almost $11 million into separating combined sewers in the downtown over the last three years. These measures help mitigate the sewer system by reducing, or even eliminating, the chance of wastewater overflows. 


Last modified:Wednesday, October 07, 2020