LONDON—In some of the great cities of Europe—Paris, Vienna, Prague, and Brussels—tourists bored with life above ground can descend below. All these cities have sewer museums and tours, and all expose their underbelly willingly to the curious. But not London, arguably the home of the most splendid sewer network in Europe. London's 30,000 miles of sewers don't have enough full-time workers to escort visitors. In 20 years, the number of "flushers"—now known as "wastewater operatives"—has shrunk from 200 to less than 40. I am privileged, then, to be able to tag along with an inspection looking for water leaks, on a dark London street around midnight. Night is the best time to visit sewers, because the businesses dispelling the most waste are closed, and the flows are calmer.
The street is quiet, and so are the men, in the manner of small groups of colleagues used to working together who must suddenly look after an outsider. So, they don't say much when, as I stand in the dressing compartment of the white Thames Water van (equipped with a microwave, a television, a basin, and lots of soap), they hand me thick woolen socks, white paper coveralls, crotch-high waders with tungsten soles (because tungsten grips but doesn't spark), a heavy belt holding an emergency breathing apparatus called a turtle (after the shape of its container), oversized rubber gloves, and a hard hat and miner's light. These are my lines of defense against hepatitis, rabies, methane, and other sewer scourges. But the men are my best defense, because they're the experts. Some have been working in the sewers for decades. They know them intimately. But with such a vast network, the men can't know every one. Some sewers haven't been visited for 15 years.
This one is the famous Fleet, the old river that gave Fleet Street its name; eventually it became an open sewer and then, built over with brick, an enclosed one. My guide for the night, an engaging sewer veteran named Rob, goes down the ladder first. The Fleet flow has been temporarily diverted to ease our entry, but I'm nervous, nonetheless, and I haul my legs inelegantly onto the ladder before descending slowly, my feet heavy with their tungsten load, waiting for the smell to hit me. It doesn't. People expect sewers to smell like their toilets, says Rob—like 3 million toilets—but the water content is rarely less than 90 percent, which dilutes most of the stink. At the bottom of the ladder, there is no stench, just a smell of damp and mustiness and the sight of bricks, bricks, and more bricks, stretching away in both directions for miles on end.
It's a matter of taste, of course, but I find it oddly beautiful, even though I'm walking through a foot-high flow where the odd bloated tampon or polystyrene cup floats past. No one on the five-strong team knows how old this section is, but they don't think it's one of Bazalgette's. They say his name with respect, for Joseph Bazalgette is still the emperor of London's sewers, even though 150 years have passed since he was tasked with revolutionizing them, thus ridding the city of cholera and foul smells. In 1858, the amount of sewage discharged into the Thames was so great that the curtains in the Houses of Parliament, located right on the river's banks, had to be soaked in chlorine to mask the odor. The Great Stink, as it became known, catalyzed change, and Bazalgette spent 16 years and 318 million bricks building a vast network of interceptor sewers that carried London's waste away from its center to be dumped in the river farther east. Things have changed, though river and sea dumping stopped only in 1997; now most waste is treated and incinerated in massive treatment plants at Beckton and Crossness, on the banks of the Thames in east London, and at Mogen, west of the city.
Except when it rains. Bazalgette's sewers, for all their genius, and despite Bazalgette having had the foresight to build in 60 percent extra capacity to account for growth, are a combined system for sewerage and drainage. Storm water can push the sewers over capacity, as in August 2004, when 8 million gallons of untreated sewage were discharged into the Thames, and condoms were seen floating at Kew, a part of London known for its gardens and chic streets. One of the men down the Fleet with me was in charge of wastewater operations at the time. He remembers being on television for three straight weeks, trying to defend the indefensible. "That's how the system is built," he says. It's not Thames Water's fault if people assume that things are better than they are; if they assume, as Jawaharlal Nehru once asserted, that the ceramic toilet bowl is the pinnacle of civilization and give not a thought to what happens after the flush.
Down in the Fleet, Rob shines his helmet lamp on a pipe. It's encrusted with something. "Liquid concrete!" he says with disgust. "This is a throwaway society. Out of sight, out of mind." People will chuck anything, he says. Flushers—wastewater operatives got their name because they used to flush river water into the system to help it flow—have found gold, jewelry, even motorbikes. But mostly they find cotton buds, condoms, and fat.
Fat is the worst, as I see in the next sewer of the night. After the ladder, a brick staircase winds down into the depths. But the stairs are impassable because they are covered with blocks of congealed fat. "It's the bane of our lives," says my companion. Congealed fat, from fast-food restaurants and households, causes up to half of the 100,000 blockages a year and costs $10.5 million to remove each year. The flushers don't mind their work environment. One told me, "Someone says to me, 'But that's shit,' and I say, 'It might be shit to you, but to me it's bread and butter." The smell of human waste passes, but fat always stinks, they say. You get home and shower, and you smell OK, then the smell oozes out of your pores. "Disgusting!" But little is done to prevent it; above-ground authorities are lax about enforcing "fat-traps" or encouraging fast-food restaurants to let their grease solidify and have it removed. That costs businesses money. Flushing it down the drain is selfish, but free.
In the final sewer of the night, I don't go far, because the roof is low, and I don't like crouching, so I stand still and wait just long enough to see a rat. All the flushers have rat stories—like how to kill them with a shovel or a hard hat. Flusher men exaggerate like fishermen, one saying he once saw a rat as long as his forearm. But rats are rarer than above-grounders think: They don't like water and there isn't enough food down there. It's another myth that the men find infuriating, just as they despair of the lack of curiosity of Londoners who never think that their convenience and conveniences are dependent on men who wade through brown water in the midnight hours.
Above ground, we stand round the hole, a curious-looking group of people in white suits on a major London thoroughfare. But only one man stops to inquire what we're doing. "We're opening a nightclub, mate," says one flusher, with no trace of a smile. The man nods, waits a few seconds, and then ambles off, no more questions asked.
Rose George is the author of The Big Necessity: The Unmentionable World of Human Waste and Why it Matters.