This was quite literally true. In the 1850s the river Thames was London's sewer. London was the largest city in the world, home to 2.3 million people in 1851. Cholera epidemics were frequent. In 1858 the smell from the river became so overwhelming that Parliament and the Law courts considered evacuating to Hampton Court and Oxford respectively.
After The Great Stink of 1858, measures were taken to modernise London's sewer system. Joseph Bazalgette, the chief engineer of the Metropolitan Board of Works, designed a complex system which was constructed between 1859 and 1865. This greatly improved both the smell of the Thames and the health of those living on its banks. Bazalgette's great-great-grandson is Peter Bazalgette, the man behind a number of British reality television shows.