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Fatbergs: The Growing Menace

So what exactly is a fatberg?

Fatbergs consist of clumps of fats, oils and grease (FOG) lately joined by the addition of “disposable” wipes. They can also include facial tissue, paper towels, tampons, sanitary towels, condoms, and other wastes flushed into the sanitary sewer system. As this collection of matter grows, it goes through the chemical reaction process of saponification. Saponification breaks down FOG into fatty acid salts (soap) and glycerol. Further reaction results in calcification, transforming the blockage into something more akin to concrete than lard.

The first use of the word “fatberg” was in London in 2013. A 15-ton calcified blockage, roughly the size of a double-decker bus, was discovered in a sewer line in the Kensington neighborhood. People complained about slow flushing toilets and the massive blockage was given the moniker fatberg as a descriptor. Fatberg was added to the Oxford English Dictionary in 2017, as “a very large mass of solid waste found in a sewer, consisting especially of fat and items that people throw down toilets.”

While initially used to describe large blockages, it is starting to be used for any size blockage that has calcified. Incidentally, in 2017, another fatberg was discovered in London, but this one was over 850 feet long and weighed nearly 143 tons. In Ireland, Belfast had a 300-ton fatberg and Devon found one extending 200 feet long. Fatbergs are becoming a worldwide problem.

Should communities be concerned about fatbergs? If so, why?

According to the National Association of Clean Water Agencies, U.S. municipalities, both large and small, shell out at least $1 billion annually on maintenance to remove clogs that will eventually become fatbergs. The problem has grown so large that several states are now following the example of Washington State in passing legislation mandating manufacturers of sanitary wipes to label their products with “do not flush” disclaimers. South Carolina and California are introducing similar bills to avert sewer clogging by mandating similar labeling disclaimers on similar products.

In 2017, a 20-ft. fatberg in Baltimore, MD, near the city’s Penn Station, caused two severe sewage overflows in a two-week period, including one that discharged nearly 1.2 million gallons of waste into a Maryland stream. The blockage affected at least 85% of a 24-in. wide, 100 years old pipe, which led to severe overflows. The cost to remove it was approximately $60,000 according to the Baltimore City Department of Public Works.

Here are other examples of large fatberg formations found throughout the US:

  • In 2018, in Macomb County, MI, a 100-foot long, 11-foot wide, 6-foot tall fatberg clogged the sewer system, causing sewer overflows and millions of dollars of damages to the community.

  • In 2018, the Department of Environmental Protection (DEP) of New York City responded to 2,100 fatbergs (small) in the city’s sewer system. It cost the City $19 million to remove them and repair the damage they caused. These costs are passed on to consumers in the form of higher water and sewer rates, and FOG is responsible for 71% of their sewer backups.

  • In 2020, the City of Des Moines, IA reported an increase in fatberg formations of at least 50% since the pandemic began. The Des Moines Metropolitan Wastewater Reclamation Authority attributes this to the increase in the flushing of sanitary wipes mixed with an increase of household oil disposal down the drains from kitchens. The Reclamation Authority spent over $100,000 in just 2020 to address over 30 blockages, which is a significant increase from previous years.

Are fatbergs caused entirely by grease and cooking oil?

Not necessarily. It is true that a significant part of fatberg formation is caused by obvious FOG products, such as lard and cooking oils. However, greasy or oily liquids of any kind chip in to forming these fat deposits. These other contributors include salad dressing, ice cream, butter, cheese, petroleum jelly and some personal care products. Studies have shown that many food items can contain FOG, making food waste grinders an additional part of the problem.

What steps are communities adopting to prevent fatberg formation?

Although not an exhaustive list, the growing menace of fatbergs is requiring municipalities to develop public awareness campaigns as well as food service establishment campaigns to promote some of the following basic steps for FOG and Fatberg abatement, such as: Consumer, watch what you flush – In their public awareness campaigns, communities throughout our nation are emphasizing the flush “only toilet paper and what comes out of you.” message to citizens and businesses. The toilet is not a free solid waste disposal unit.

  • Consumer and FSE – Recycle cooking oil – Cooking oil is an easily renewable energy source. Recycled cooking oil can be used in many industrial operations and processes. It is minimally refined to create biodiesel, which is nontoxic and biodegradable. Using biodiesel lowers life-cycle emissions by 74% versus petroleum diesel. Municipalities are encouraging restaurants and residents to contact local companies to collect solidified cooking oil in order to make biodiesel. In rural areas many farmers will take it and use it to supplement the fuel in farm equipment.

  • Consumer – installing residential grease traps – Installing a residential grease trap can help reduce the amount of fat and oil that ends up down the drain. Installed below your sink, grease traps (technically interceptors) will separate FOG from your wastewater so it doesn’t end up in the sewer. Regular home maintenance is required.

  • Consumer – install bidets or bidet attachments to your toilets – If you use “flushable” wipes to clean yourself, a bidet can do an easier, more thorough job with just warm water.

  • FSE – route all fixtures and drains through an appropriately sized and maintained grease interceptor. This has been proven to reduce FOG discharge by as much as 300% to over 1500%.

  • FSE – sign up for one of the free FOG Abatement Program workshops funded by the USDA Rural Development Program and provided by the Western States Alliance. Register at: or contact More resources at

  • Consumer include reference in your public awareness program to the 5 most harmful pump and sewer clogging materials:

  • Fats, Oils and Grease

  • Flushable Wipes

  • Disinfecting Baby Wipes

  • Feminine Hygiene Products

  • Paper Towels


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