Fatberg hit squads are tackling mountains of fat in Merton's sewers.

Thames Water is surveying and cleaning more than 1,100km of sewer - enough to stretch from London to John O’Groats.

Mitcham has been identified as a fatberg hotspot, along with Belvedere, Newham, Stratford, Ilford, Wanstead, Stoke Newington, Finchley, Hornchurch, Romford, Southall, Hayes, Greenford, West Drayton, Streatham, Hounslow, Harrow, Pinner, Wembley and Barking.

They are also sending Bin it - don’t block it kits to 40,000 households in top blockage hotspot areas across London and the Thames Valley.

The kits contain fat traps to collect used cooking oil, as well as food scrapers and sink-strainers, designed to keep sewer-unfriendly items out of the drains.

It is hoped people will be encouraged urge not to wash food fat and wet wipes down drains as they clog sewers and can cause homes and streets to flood with sewage, as well as harming wildlife by polluting rivers.

Rob Smith, Thames Water’s chief sewer flusher and key member of the fatberg hit squad, said: "The sewers serve an important purpose - they are not an abyss for household rubbish. Fat goes down the drain easily enough, but when it hits the cold sewers, it hardens into disgusting fatbergs that block pipes.

"Wet wipes cling to the fat. Fat clings to the wipes. And pretty soon your fatberg is out of control and sewage is backing up into roads, gardens and in the worst cases flooding up through toilets and into homes.

Fatberg's hit the headlines in August when a 15-ton fatberg was discovered in a Kingston sewer.