A Brief History of London's Sewer System

After years in this industry, I still didn’t know that the word ‘sewer’ comes from Old English, meaning seaward. The sewers in London were open ditches which sloped downwards slightly in the center of the street. Into these channels was thrown all manner of human and household waste, and they filled to overflowing very quickly. Overflows mean that the waste had to have somewhere to go...that somewhere was into people’s houses and marketplaces.

An edict written by Henry VIII in the late 1500s ruled that people be responsible for clearing the sewer passing by their dwelling. As with many clean air and clean water laws today, this law didn’t really come into effect until 1622 when they had the funds to enforce it.

Despite all good intentions and efforts, the waste in London was a constant problem and the hazards of poor sanitation were a permanent health threat. By the early 18th century the vast majority of residences had a cesspit beneath the floorboards. This meant that even in the best of homes, the smell of the ever present waste was positively nauseating, rendering indoor odors worse than those on the streets.

In the evenings, the fear of the ‘night air’ meant all doors and windows were shut at dusk, supposedly shutting out the coal smoke and sulfurous industrial fog. Little did they know that the noxious gases indoors were far worse for their health. There were numerous reports of entire families dying of apparent ‘asphyxiation’ during the night. Looking back at the medical reports of these cases, it is evident that the injuries were consistent with oxygen deficiency and other such maladies still seen today in sewers.

The cesspits in the then ‘modern’ houses were built to overflow into the sewers along the streets. As the overflow channels were often blocked, the waste had nowhere to go other than to soak into the foundations and wells, the source of drinking water for neighboring families. To compound the problem, chamber pots were replaced by Thomas Crapper’s flushing toilet which dramatically increased the amount of water and waste flowing into the cesspits.  (And now, incidentally, you understand the origination of an oft used slang word today!)

Dr John Snow (1847)

In 1854, Dr. John Snow made a major medical discovery, proving that cholera was a water-borne disease by tracing the start of an epidemic to a single polluted water pump.  The London cholera epidemic of 1848-1849 killed 14,137 Londoners.  Now that the culprit was identified, sanitation reform became a high priority.

The consolidation of local councils, which named themselves the Metropolitan Commission of Sewers, was established in 1848.  It surveyed London's antiquated sewerage system and set about ridding the capital city of an estimated 200,000 private cesspits.

The impetus for this plan was accelerated by the "Great Stink" during the unusually hot summer of 1858. The River Thames was basically one huge sewer, devoid of any fish or wildlife, and the hot weather encouraged bacteria in the ‘water’ to thrive, making the smell thoughout the city almost unbearable. The smell was such a problem that the House of Commons considered relocating upstream to Hampton Court until heavy rains broke the spell and smell of heat! But the rain only temporarily alleviated the immediate crisis, the main health problem was ever present.

The Metropolitain Commission of Sewers was replaced in 1855 by the Metropolitain Board of Works, headed by Chief Engineer Joseph Bazalgette. Bazalgette developed the solution to London’s problem by designing the construction of 83 miles of underground specially developed brick main sewers to intercept sewage outflows.  These main tunnels would connect to over 1,000 miles of street sewers that intercepted the raw sewage which up until then flowed freely through the streets and thoroughfares of London. The outflows were diverted downstream of the City where they were dumped, untreated, into the Thames. Extensive sewage treatment facilities were built only decades later.

Bazalgette’s plan involved four major pumping stations, constructed between 1864 and 1875. The station at Abbey Mills (known as the The Cathedral of Sewage) in the River Lea Valley, was contructed in 1868 and still stands today. Although it is no longer in daily service, it does have electrical pumps and now functions only a backup to the modern pump station.

The original Abbey Mills Pumping Station

The new Abbey Mills Pumping Station

Bazalgette's amazing foresight is evident in the diameter of the sewers he designed. When planning the London network, he took the largest demographic area of the city and applied it to the city as a whole.  He calculated for every person the most generous allowance of sewage production and came up with a diameter of pipe needed based on those figures. Bazalgette was a believer in the concept that “one always has to expect the unexpected” and was not planning on undertaking the task of building the sewer system second time.  Therefore, he doubled the diameter of the pipes to be used. Every Londoner should be grateful for this foresight as the unforeseen and unexpected at that time in history was the highrise building! Had his original diameter been used, the smaller pipe would have overflowed in the 1960s. As is, they are still in use to this day!

Deptford pumping station 1860-1862 (11ft. 6in.)

London’s Victorian sewers today.