A 64-metre-long fatberg has formed in the sewers of an English seaside town, the largest ever discovered in the area.

Key points: The fatberg has not affected local swimming water quality

The fatberg has not affected local swimming water quality A massive London fatberg was put on display in a museum after a two-month removal process

A massive London fatberg was put on display in a museum after a two-month removal process Breaking up and clearing fatbergs from sewers costs millions annually

Crews will spend an estimated eight weeks below Sidmouth, in Devon, using shovels, pickaxes and high-pressure cleaning equipment to break up and remove the congealed monstrosity.

"It is formed from everything that has been flushed or poured down the sinks of Sidmouth that shouldn't have been, including wet wipes and fat, oil and grease," the local water authority South West Water said.

The treatment manager for the authority, Andrew Rowntree, said the takeaway message for people was around how to use their toilets.

"Only flush the three Ps: that is pee, paper and poo. And nothing else," he said.

"Everything else needs to go in the bin and the same applies with fat in the kitchen sink, don't pour hot fat down the kitchen sink, it needs to go into a container and also put in the bin."

The fatberg will take crews months to break up and remove. ( Supplied: South West Water )

The fatberg, which stretches longer than six back-to-back double-decker buses, has not impacted swimming water quality in the area and nearby coastal walking paths will remain open while it is being dealt with.

In September 2017, a 250-metre-long, 130-tonne fatberg was found in the sewers of the London suburb of Whitechapel.

The mass of congealed fat, wet wipes, nappies and condoms was as hard as concrete and took workers more than two months to remove.

Once they were done, samples were taken.

The still-hazardous remnants were air-dried, then locked inside specially sealed units and put on display in a temporary exhibition.

London's Thames Water — the UK's largest water and wastewater services company — clears one sewer blockage every seven-and-a-half minutes and spends about $1.8 million each month removing them.

A fatberg inside a sewer in Whitechapel, London, in September 2017. ( AP: Thames Water )

Most of Whitechapel's monster fatberg was melted and converted to biofuel that could be used to power vehicles such as London's buses.

In Australia, Brisbane's sewers have also been blocked by large fatbergs, with up to 4,000 blockages cleared across Brisbane, Ipswich, Lockyer Valley and Scenic Rim at a cost of $1.5 million.