Thames Water said a blockage weighing around 100 tonnes was cleared from a west London sewer in Feltham. The mass, located more than 10 metres below street level, was mainly made up of wet wipes bound by fat, oil and grease and was described as the equivalent of eight double-decker buses.

A specialist team accessed the sewer via a large manhole chamber equipped with gas monitors, then used blasting, chiselling and suction to remove the obstruction along about 125 metres of pipes. The waste was loaded into skips and taken to landfill.

Alexander Dudfield, engagement lead for network protection at Thames Water, said the clearance was highly complex for engineers and illustrated the challenges faced. He noted that some blockages in the largest sewers can weigh as much as 25 elephants, but most occur in local pipes, which are often narrower than a mobile phone and usually stem from household waste. When these pipes block, sewage cannot simply be switched off and can back up into roads, rivers or homes with potentially serious consequences.

Earlier this month, the Port of London Authority, Thames21 and Thames Water worked together to remove a bank of wet wipes that had settled into sludge on a curve of the River Thames near Hammersmith Bridge. Thames Water urged the public not to flush wet wipes and to dispose of waste other than toilet paper. The company says wipes are a common cause of sewer blockages and it clears about 75,000 blockages a year, removing around 3.8 million items annually in operations costing £18 million (€20.9 million). So far this year, it has cleared 28,899 rag blockages, 14,810 fat, oil and grease blockages and 686 third-party blockages.