The Great Stink

In the summer of 1858, London smelled so appalling that the people who governed the country could barely bear to sit in their own building. June was unusually hot, and the Thames, which flowed past the newly rebuilt Houses of Parliament, had become little more than an open sewer. Its banks were coated in a thick, dark mud of human waste, and on the warmest days the stench drifted through the windows of the debating chambers. The newspapers soon gave the episode the name by which it is still known: the Great Stink.

The crisis had been decades in the making. London's population had more than doubled in the first half of the century, to well over two million people, yet much of its waste still went into cesspits beneath houses or into old drains that had been designed to carry rainwater. Ironically, a symbol of progress had made matters worse. As the flushing toilet spread through middle-class homes, ever larger volumes of water and sewage were sent into the drains, and the drains emptied straight into the river from which many Londoners still drew their drinking water.

Most experts at the time believed that disease was spread by miasma, or foul air. If something smelled bad, the reasoning went, it was probably dangerous. A few dissenters disagreed. The physician John Snow had argued, most famously during a cholera outbreak in Soho in 1854, that the disease was carried in contaminated water, and he had traced many of the cases to a single public pump. His ideas, however, were far from widely accepted, and he died in June 1858, in the very month the river began to stink, without seeing them vindicated.

What eventually moved Parliament was not the evidence about cholera but the smell itself. Curtains soaked in chemicals were hung at the windows, and there was even talk of moving the business of government out of London. Benjamin Disraeli, then leading the House of Commons, is said to have fled a committee room with a handkerchief pressed to his nose, and in one speech he reportedly described the river as a pool reeking with unbearable horrors. Within a matter of weeks, a bill had been passed giving the Metropolitan Board of Works the power, and the money, to solve the problem. A project that had been debated for years was suddenly about to begin.

The man in charge was the Board's chief engineer, Joseph Bazalgette, and it was a task that was to occupy him for the better part of two decades. His plan was as simple in principle as it was immense in scale. Instead of letting countless drains empty into the Thames, a network of large intercepting sewers would run parallel to the river, catching the waste and carrying it, largely by gravity, several miles east to outfalls beyond the city, where it would be released on the outgoing tide. Pumping stations, built with surprising elegance, would lift the sewage wherever the ground was too flat. In all, the scheme would involve well over a thousand miles of sewers, from great brick tunnels beneath the main roads to the smaller pipes beneath individual streets.

Bazalgette was known for his caution. According to a story that engineers still like to repeat, he calculated the size of pipe each district would need and then doubled it, reasoning that the job would only ever be done once. Whether or not the anecdote is exactly true, the generosity of his design is one reason why much of his system is still in use today. Along the river, his sewers were buried beneath new embankments, which also gave London wide roads, gardens and, in time, a route for the Underground.

The main system was officially opened in 1865, though work continued for another decade. A year later, cholera struck London once again, and most of the deaths occurred in a part of the East End that had not yet been properly connected. For many observers, it was further evidence that Snow had been right. There is a final irony in the story: the sewers were built to get rid of a smell, on the strength of a theory that turned out to be wrong, and yet they did more for the city's health than almost any other reform of the century. By the early twenty-first century, the old network was struggling to cope with a city of some nine million people, and a new tunnel, nicknamed the super sewer, was dug beneath the Thames to relieve it. Bazalgette, one suspects, would have approved.