Pictures: Walls of Fat Clog London Sewers

Before: Fat "Ceiling"

Photograph courtesy Thames Water

Fat thickly coats a Thames Water-administered sewer in Reading (map), U.K., in May 2009.

The fat "ceiling" is the result of years of what the company calls sewer abuse—the pouring of food waste down sinks and the flushing of items other than toilet paper and human waste.

Once in the sewers, leftover meat fat gets mixed in with items like makeup wipes, diapers, cotton balls, condoms, and sanitary napkins, said Amy Dutton, a spokesperson for Thames Water, which is responsible for wastewater treatment for various U.K. jurisdictions.

"It all gets caught up with the fat, and the fat congeals," she explained. "And that's what causes the blockage."

(See a picture of a hotel room in a section of sewer pipe.)

Published July 20, 2010

After: Spic 'n Span Sewer

Photograph courtesy Thames Water

The same Reading sewer, newly de-fatted in May 2009, is testament to the flushers skill with shovels and high-pressure water hoses.

As if the job weren't dirty enough, the flushers face giant rats, revolting smells, and potentially lethal cocktails of sewer gases such as methane and hydrogen sulfide, Thames Water's Amy Dutton said.

Workers are equipped with breathing apparatuses, emergency oxygen supplies, and gas-detection monitors, Dutton added.

"If the gas monitor goes off, they have to get out pretty quickly," she said. "It's not a nice job to have."

Published July 20, 2010

Flushed Away

Photograph courtesy Thames Water

Flushers de-fat a London sewer in an undated picture.

Thames Water says it has to tackle around 55,000 blockages a year in London and the surrounding Thames Valley region. Most are caused by cooking fats and oils, which congeal to form a thick, putrid layer around drains and sewer walls.

The brick sewer system under central London is particularly vulnerable to blockage, given its mid-19th century vintage and the huge number of restaurants in the area, Thames Water's Amy Dutton said.

Published July 20, 2010

Down the Manhole

Photograph courtesy Thames Water

Seen from street level, a London sewer drain is caked with fat in 2005.

"If the sewage can't pass a blockage, it will back up and come out through the manhole into streets or up through people's toilets," Thames Water's Amy Dutton said.

The water company is encouraging London restaurants to recycle their cooking fat instead of pouring it down the drain. "They have their fat collected and it gets turned into biofuel," Dutton said.

Once in the sewer, though, the fat can't be turned into fuel, as it becomes tainted by other waste and trash, she said. (See biofuel pictures.)

Published July 20, 2010

Trimming the Fat

Photograph by Luke MacGregor, Reuters

A Thames Water "flusher" removes fat deposits from a London sewer wall in 2007.

Workers who ventured beneath Leicester Square last week said they couldn't even see the sewer it was so crammed with fat. "You actually have to break it with a shovel," flusher Danny Brackley said. "That's how hard it is."

Seeking leaner sewers, Thames Water has launched a campaign to educate Londoners on what should and shouldn't go down the drain.

For home kitchens, the company recommends leaving leftover cooking fat to cool, then putting it in a garbage can, or mixing the fat with seeds and nuts for a DIY bird feeder.

(Related: "Alcohol, Feces, Carcasses Fuel 'Green' Vehicles in Sweden.")

Published July 20, 2010