By the middle of the 19th century, the streets of London ran with human filth. For centuries, the city had depended on a patchwork system of local waste disposal, relying on night-soil collectors who would empty local cesspits, and on the city's old rivers, like the Fleet and the Tyburn, now little more than open sewers. The increasing use of the flush toilet only made things worse, letting wealthy families dump their poo straight into the river. Most of the inhabitant's faeces and urine was eventually dumped into the Thames, which also served as a source of water for drinking and washing. The Metropolitan Board of Works had wanted to improve London's sewers for years, but didn't have enough money.
The summer of 1858 saw the "Great Stink" overwhelm London. The hot weather exposed the rotting human effluent and industrial waste polluting the water of the Thames. Water-borne diseases like cholera and typhoid fever swept through the population. It was believed that the smell itself, or "miasma", spread these plagues, and those who could afford to fled the stinking city.
Such was the overpowering smell from the Thames, the curtains of the Houses of Parliament were soaked in chloride of lime in a vain effort to block out the smell. It is no surprise that a bill was rushed through Parliament and became law in just 18 days, to provide more money to construct a massive new sewer scheme for London. The Times newspaper said that Members of Parliament had been "forced by sheer stench" to solve the sewer issue.