Whenever you see sewers in films, they’re always miraculously well-lit and unnaturally clean. Take that scene in the new Spiderman film when Rhys Ifans as Dr Curt Connors plots in his underground lizard lair, or in the Disney cartoon Ratatouille when the rats flee on mini boats, white water rafting style down into Parisian sewers.

What these scenes never show is the disgusting flow of effluence and filth which gushes and gathers in clumps along the tunnels deep under the pavement. The Teenage Mutant Ninja Turtles never had to wade through sh*t. If they had, their shells would have been a heck of a lot less shiny!

Yesterday I had the somewhat debatable honour of a trip down a manhole into one of the sewers in the heart of London just along from Trafalgar and Leicester Squares.  As puzzled tourists and theatre goers looked on, I zipped up a white, full-body ‘paper suit’ (hoping it was a bit more substantial than it sounds), stepped into thigh-high river waders and snapped on rubber gloves. I was excited – until I looked down the manhole. My tummy plunged. That first step onto the ladder down into darkness was a nervous one.

Hitting the bottom, I couldn’t see anything in the black but slowly my eyes adjusted. Then a piercing beam from the headlight on Rob’s helmet – the Thames Water man who was taking me down there – revealed a long, low tunnel. The smell wasn’t too bad. Yet.

Tramping down the dry tunnel of about three feet wide and six high took us to a T-junction where it met another smaller tunnel, which carried a steady stream of water down towards some steps a few feet further on. In the water were dirty baby wipes, chunks of poo, balloon-like, bloated condoms filled up with filthy water and fat. All gushed along, waterfall-like toward the steps. At the bottom, they had formed what the sewer team call a ‘fat-berg’.

Yep, you heard right. An iceberg of fat. Gross.

There was enough space in this wider part of the sewers for the smell to be bearable and despite what you would think, you don’t notice it most of the time – but when it did occasionally rise up and hit your nostrils, it was…..yep vom inducing!

So why was I down in the murky stink with ELN cameraman Simon and some of the Thames Water workmen? Good question. Because the fat and cooking oil tipped carelessly away by homes and local restaurants which ends up as congealed gunk contributes to the 80,000 blockages that Thames Water deals with every year. At a million pounds a month to solve, that’s a big old spend.

In a stroke of recycling genius, some bright spark has found a use for the yucky goo: a fat-fuelled power station. So along with energy firm 2OC, they’re going to collect that grease from restaurants in the city with ‘fat-traps’ and truck it out to a new plant in Beckton.

While it will cost £60million to build the plant, it’s going to save Thames Water an awful lot of money on energy bills – they’ve agreed to buy 60% of the electricity. With energy prices going the way they are (i.e. ever upwards) I think we’re going to see more and more like this classic example of waste not, want not.

Watch out for my film on ELN next week and be grateful no one has invented smell-o-vision yet!