A grotesque lump of festering food fat and improperly flushed wet wipes accumulated to a mass the size of a double-decker bus in the sewers of London, and officials say that if they had not found and removed it in time, it could have led to sewage flooding homes, streets and businesses.

The people charged with the messy task of cleaning the sewer are calling the putrid lump a "fatberg."

"We clean hundreds of meters of sewers weekly and this is one of the worst we've seen," Gordon Hailwood a supervisor from Thames Water waste management told the BBC.

He said the fatberg amounted to "15 tonnes of fat and debris all congealed in one lump in a sewer."

It took sewage crews three weeks to remove the fatberg. If it has not been properly disposed of, the sewers would have backed up and made a mess of the leafy suburb above London Road in Kingston, Surrey.

Hailwood said had the mass of waste of fat not been discovered, it "could have started spurting out of manholes across the whole of Kingston."

Crews used a jetting technique that broke the fat into smaller lumps and then sucked them into a storage tanker, which hauled the mass to a waste discharge center.

"While we've removed greater volumes of fat from under central London in the past, we've never seen a single, congealed lump of lard this big clogging our sewers before," Hailwood said in a statement.

"Given we've got the biggest sewers and this is the biggest fatberg we've encountered, we reckon it has to be the biggest such berg in British history."

The blockage was discovered after residents complained of not being able to flush their toilets. Investigators found that the fatberg had reduced the 70 by 48 centimeter (28 by 19 inch) sewer to just 5 percent of its normal capacity.

The incident was made public to highlight to the public the damage and strain caused to sewer networks, Hailwood said.

"Homes and businesses need to change their ways, when it comes to fat and wipes, please remember: 'Bin it -- don't block it.'"