London in 1858 was a city of nearly 3 million people, and every one of them flushed into the Thames. The river had served as London's sewer for centuries, but the introduction of flush toilets - paradoxically - made things worse. Instead of human waste sitting in cesspits, it now flowed directly into the river.

The Thames by 1858 was an open sewer. The water was brown, viscous, and reeking. Fish had died off decades earlier. Londoners who could afford it drank beer or bottled water. Those who couldn't risked cholera with every drink. But as long as the smell was contained to poor neighborhoods, the wealthy showed little interest in reform.

The summer of 1858 was unusually hot. The Thames, at its lowest summer level, became a concentrated stew of human waste baking in the sun. The smell that had always been bad became intolerable. It wasn't just unpleasant - it was thought to be dangerous. The prevailing 'miasma theory' held that disease was caused by bad air, and the air coming off the Thames was as bad as it could get.

The smell permeated Westminster. The new Houses of Parliament, completed just two years earlier, had been built directly on the riverbank. Their designers had not anticipated that Parliament would be downwind of an open sewer.

Members of Parliament tried everything to escape the smell. Curtains soaked in chloride of lime were hung over windows. This only partially masked the stench and added a chemical tang. Committees moved to rooms on the opposite side of the building. The smell followed. A proposal was floated to move Parliament to Oxford or St. Albans until the smell subsided.

The newspapers had a field day. Punch magazine published cartoons of Parliament fleeing the river. Editorials demanded action. The Thames, once the symbol of British commerce and power, had become a national embarrassment. Something had to be done.

The Great Stink accomplished what decades of public health campaigning had failed to achieve. Benjamin Disraeli, the Chancellor of the Exchequer, introduced a bill authorizing construction of a proper sewer system. The bill, which might have taken years to pass under normal circumstances, was approved in eighteen days.

The legislation authorized Joseph Bazalgette, chief engineer of the Metropolitan Board of Works, to build an intercepting sewer system that would capture London's waste before it reached the Thames and carry it downstream to treatment works. It would be one of the greatest civil engineering projects of the 19th century.

Bazalgette's sewer system took over a decade to build. It included 82 miles of main sewers, 1,100 miles of street sewers, and the magnificent Victoria Embankment, which covered a new sewer along the north bank of the Thames and created new land for roads and gardens.

The system still serves London today. Cholera epidemics stopped. The Thames, though never pristine, recovered enough to support fish again. The Great Stink was a turning point in the history of public health - the moment when government accepted responsibility for sanitation. It had taken unbearable stench to convince Parliament. But once convinced, they built for the ages.