How Fats, Oils, and Grease Affect the Sewer System

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Cut away from a clogged sewer pipe that is full of grease

The City's sanitary sewer system is made up of pipes called sewer mains and laterals which connect our homes and businesses to public sewage treatment facilities. Sewer laterals run underground connecting your house to the public sewer main under the road.

In January 2014, this video of a residential sewer lateral pipe was recorded in Niagara Falls.  Here's a similar video of a Niagara Falls sewer main.

When fats, oils, and grease are flushed down sinks, drains, or toilets, it causes problems for both you and the City.  These blockages will gradually restrict the flow of wastewater from your house, leading to sewage back-ups and the resulting damage.  They also deposit grease in the public sewer main which negatively impacts the City’s sewer system and can cause problems for numerous houses.

How do fats, oils, and grease cause sewer blockages?

When fats, oils, and grease are poured or flushed down your sinks, drains, or toilets they enter the sewer system where they cool, harden and stick to the inner walls of sewer pipes. Over time, as more fats, oils, and grease are added to the system, these sewer blockages build-up and harden until they completely plug the pipes.  The hardness of the blockages makes them very difficult and costly to clean out.

Where do fats, oils, and grease come from?

The most common sources of household fats, oils, and grease are:

  • meats and other food scraps (including baked goods)
  • sauces, gravies, and salad dressings
  • dairy products (milk, cream, yogurt, kefir, cheese)
  • fats, lards, cooking oil, shortening, butter, and margarine
  • cosmetics and toiletries (makeup, lotions, some soaps and oils)

How do these blockages affect the sanitary sewer system?

You may think that once you flush it, it simply washes away and is gone for good. That’s not the case. Fats, oils, and grease will build up in your pipes, create blockages and plug sewers, leading to problems such as:

  • Raw sewage overflowing and backing up into your home, business, or a neighbouring property.  
  • Basement flooding (an expensive and unpleasant situation).
  • Exposure to disease-causing organisms.
  • Raw sewage overflowing into parks, yards, streets, creeks, rivers and the lake.
  • Increasing operations and maintenance costs to clean and repair damaged sewer pipes.

How can you help prevent sewer system blockages?

  • NEVER pour grease down drains or into toilets.
  • ALWAYS use drain baskets/strainers to catch food scraps and other solids. Empty the basket/strainer into your Green Bin.
  • BE AWARE: depositing any matter capable of obstructing the flow of, or interfering with the operation of, a sewer is enforceable through the Region’s Sewer By-Law – 47-2008.

What should you do with your fats, oils and grease?

  • Let the grease cool and harden, then scrape it and food scraps from trays, plates, pots and pans, utensils, grills, and cooking surfaces into your Green Bin.
  • Small volumes of liquid cooking oil can be placed into the Green Bin as long as the oil can be absorbed by the other organic materials or paper towels.
  • Larger amounts should be collected into a sealed container labelled “cooking oil” which can be dropped off at household hazardous waste depots on community environment days. See the Niagara Region’s website for more information.

What is the City of Niagara Falls doing to address the problem?

The City regularly inspects sewer mains and cleans with high pressure or mechanical devices. Typically, the City inspects all sewer mains once every five years. Additionally, sewer mains are video inspected to determine the condition of the pipe at the time.

In some areas, a more frequent cleaning schedule is required to remove accumulated grease and debris that is in the main. Sometimes grease and debris completely block the sewer main resulting in sewer back-ups to home.

The City responds immediately to clear the main and blockage. In freezing temperatures, this incrusted grease is almost impossible to remove, and high pressure equipment freezes making removal a difficult task. Mechanical methods can be used to dislodge stubborn incrustation, but this can be damaging to the sewer mains.

If during the process of investigation, any structural defects are found, the City immediately schedules repairs to sewer mains or laterals, to fix the problem.