Charlie Ewart, a 51-year-old father of two from Plymouth, has been battling blockages in the sewers of south-west England for 15 years.

But even he was not prepared for the dreadful sight, and smell, of what he found lurking beneath the elegant seafront in the regency town of Sidmouth when he scrambled through a small manhole.

“I saw it and thought: ‘What on earth?’ It was completely unexpected,” Ewart said. “It’s really eerie in that bit of the sewer and it does look like something out of a horror scene, all congealed and glossy and matted together with all kinds of things.”

Happily for Ewart, it was not a monster risen from the depths or from outer space but rather a fatberg – a mass of congealed oils, grease wet wipes and other nasties measuring the size of six double-decker buses.

Sidmouth’s fatberg, which has been gathering beneath beneath the Esplanade for years, has provoked interest around the world. Visitors have arrived in Sidmouth to examine the spot and try to pick up a whiff. South West Water is opening a pop-up shop to explain what is happening and warn people of the dangers of dropping things they shouldn’t down the toilet and sink.

Meanwhile, Ewart and his hardy colleagues have the job of getting rid of the 64-metre-long object.

“The sewer will be active while we carry out the removal, so depending on the flows, we could be wading through a lot of muck,” said Ewart.

“We are going to be using small shovels and something called a mattock – this is like a lighter version of a pickaxe so we won’t tire as quickly. We also have special high-pressure sewer jetting equipment and something to suck it out in bits.

“I think this fatberg is going to be soft on the outside but hard in the middle. I’m not too sure what is within it yet, there’s a lot of wet wipes and sanitary wrappers, but I’ve tried not to look at it too closely yet, especially as I’m going to be staring at it for eight weeks.”

The team will have to wear breathing apparatus when they are underground. The smell is not pleasant, a heady combination of rotting meat mixed with the odour of an unclean toilet. Yet despite admitting to having a phobia of rats, Ewart said he was relishing the challenge.

“It’s not a job for everyone but I take a huge amount of pride in what I do. People don’t think about it when they put things down the loo or sink, but someone has to deal with the consequences.”

The tale of the Sidmouth fatberg provides an insight into the changing nature, good as well as bad, of the UK’s attitude to sewage – and the nation’s toilet habits.

It nestles in what was a large holding tank built in Victorian or regency times. In those days, the town’s raw sewage would be held in the tank and simply released on an outgoing tide. After the privatisation of the water industry in 1989, South West Water introduced its £1.5bn Clean Sweep programme designed to improve the quality of sea water for bathers.

As part of the project, a large pumping station was built at the end of the Esplanade. Sewage now flows through the holding tank where the fatberg resides and is pumped up to a treatment works inland at Sidford. After being treated it is piped back down to the sea and treated effluent is discharged into an offshore outfall. It is now safe and enjoyable to bathe off Sidmouth.

So far, so good. But in recent years some people have begun to put more and more objects down the toilet and continued to pour oil and fat down the sink.

South West Water’s director of wastewater, Andrew Roantree, said the industry had become accustomed to dealing with condoms, nappies and sanitary products. But then came the wet wipe.

“The proliferation of wet wipe-type products has started to generate a real problem,” said Roantree. “The wet wipes tend to create a matrix that all these other things get caught up in.” In a kind of snowball effect, the wet wipes congeal with fats, oil and grease, gradually forming a hard mass.

But why did nobody notice the Sidmouth monster forming? For a start, the network is huge – South West Water looks after more than 10,000 miles of sewer pipes. And the size of the tank under the Esplanade, up to three metres high in places and as wide as the street, meant that sewage and discharged water was not blocked by its mass. The waste carried on reaching the pumping station at the end of the Esplanade and no alarm bells were sounded.

The fatberg is estimated to have had two years to develop before Ewart found it, close to the yacht club and RNLI lifeboat station. Its removal is expected to cost £100,000 and some south-west residents have questioned why they should have to pay for a Sidmouth problem.

But Roantree said the company spends about £5m a year on clearing blockages of all shapes and sizes from across its region. “We have 8,500 blockages a year. It happens right across our region.”

South West Water is keen to get over the message that only the “three Ps” – poo, pee and paper – should end up in a toilet.

The last word should surely go to the heroic finder and, hopefully, vanquisher, of the fatberg.

“I’m married and have two girls,” he said. “I have made sure to educate my family on what they put down the loo and sink. My elder daughter loves makeup, but she knows not to put wipes of any kind down the toilet.

“We even use cheap toilet roll, which goes down the loo much easier than the thicker stuff. When you see the consequences like I do, you make sure to do all you can, even if it’s just so you don’t block up your own pipes.”