It is a large mass of fat and solid waste that collects in a sewer system.
In the last decade or so, there has been news out of the UK relating to what has been described as fatbergs. These are large globs of grease, fat and undegradable wet wipes and diapers that have been clogging UK sewers. One as large as 64 meters was discovered under the streets of Devon England.
Even worse, in 2017 a 150-ton, 820-foot-long fatberg was discovered in the sewers beneath east London.
“Workers then have to break them up using pickaxes or shovels, or blast them with high-pressure water jets.”A fatberg longer than the Leaning Tower of Pisa is clogging another UK sewer – Business Insider
Many of the sewers in the UK were old, built during Victorian times, making them particularly prone to this type of occurrence in this time of non-degradable products being marketed as “flushable”. However, many other cities around the world have had to deal with problematic fatbergs.