McDonald's is joining the fight against 'fatbergs' by adapting its washing machines to better extract grease, in a bid to help local authorities tackle the fat-based blockages that clog Britain's sewers. 

Working with domestic appliances manufacturer Miele, the fast food giant is set to adapt the washing machines used in its 1,300 UK restaurants to better enable the extraction of grease and fats and minimise drainage issues.

The firm will then use the grease extracted in these wash cycles to boost its biofuel production, which helps fuel its lorry fleet.

McDonald's has used specialist grease recovery units (GRUs) for several years, but the high temperatures used for grease removal limits the lifecycle of the machines and makes it difficult to separate and extract the grease. The firm worked closely with Miele to adapt its washing machines, replacing the hoses, valves and door seal with silicon-based items to make them more durable and hard-wearing.

"Miele continues to assist us with our washing requirements to make our grease recovery process more effective and help McDonald's Restaurants become more sustainable," said Dave Holden, building services consultant at McDonald's. "The introduction of the GRU has enabled us to service more of our vehicle fleet with biofuel and with further modifications we expect this to increase further."

So-called Fatbergs - large balls of waste that are caused by the build-up of wet wipes, nappies, fats, oils, and grease - have become increasingly common in recent years, according to trade body Water UK. Sewer blockages are estimated to cost the UK £100m each year, as well as contributing to harmful sewer flooding.

By far the biggest culprits are wet wipes, estimated to be responsible for 93 per cent of material causing blockages. The disposable cloths are also causing problems above ground, with bundles such as the ‘Great Wet Wipe Reef' in Barnes - estimated at 50 metres wide, 17 metres long and one metre high - reshaping riverbanks and harming wildlife.

Earlier this year, Water UK launched a new industry standard to help consumers identify which wet wipes can be safely flushed down the toilet. Manufacturers of wet wipes which pass scientific tests set under the new 'Fine to Flush' standard will be allowed to feature a logo on their packaging, signalling to consumers that they can be flushed without risk of creating fatbergs.

The move followed a BBC investigation which found no wet wipes sold as flushable in the UK had passed the water industry's disintegration tests.

A fragment of a 130-tonne fatberg that blocked a 250-metre stretch of London's sewer network was displayed in the Museum of London in 2017, after engineers used shovels and high-powered jets to dismantle the colossus.