A disgusting, congealed blob of fat, oil, and other unpleasant household waste has been discovered blocking a major sewer line underneath London.

The so-called "fatberg" weighs 143 tons, and is currently clogging a 820-foot stretch of piping below ground in east London.

Sewer workers investigating the 'berg say that over time it has solidified, and is now as difficult to remove as concrete.

The blockage was formed over years, as oily liquids and household products like wet wipes and diapers have been flushed or dumped into water pipes.

A map showing the fatberg's approximate location in London. Google Maps/Business Insider

Workers are currently waging what sewage company Thames Water describes as "a three-week sewer war" to liquefy and remove the fatberg.

Eight workers are using high-pressure jets of water to break up the blockage, which is then sucked into waiting tankers and transported to a recycling facility.

Another view of the fatberg. Thames Water

The operation is part of a constant effort to keep London's sewage infrastructure functioning after more than a century of constant use.

The sewer inhabited by the Whitechapel fatberg was built in the Victorian era. It is supposed to provide a pipe for waste to flow through that's 4 feet tall and 2.3 feet wide. But it's currently mostly unusable.

A Thames Water worker heads into the sewers to battle the fatberg. Thames Water

London has been plagued by fatbergs before, spawning an entire industry of "flusher" technicians fighting back against the encroaching slime.

In 2014, Thames Water mounted an emergency operation to stop Whitehall, the administrative heart of the British Government, from being overwhelmed by one of the blockages.