Fat in a Sink, Wipes in a Loo—How Fatbergs Are Born

The most disgusting thing you’ve never heard of is haunting sewers around the world. Fatbergs, as they’re called, are deposits of fat and grease mixed with non-dissolvable waste. Each one is a profile of what urban denizens are improperly flushing down toilets and pouring down sinks. Increasingly, they are trouble for sanitation systems, which bear the burden of removing them so sewage can flow freely to water-treatment plants.

London sewage workers are said to have combined “fat” and “iceberg” to coin the term. London, with a sewage system dating back to the late 1800s, has been ground zero for the fatberg problem. The American Dialect Society named fatberg one of the most outrageous words of 2013. Australians call the accumulations “sewage sheep.”