Late great engineers: Joseph Bazalgette - London’s engineer

With public health very much at the top of the agenda at the moment, we look back on the life and times of Joseph Bazalgette, the civil engineer who saved London from cholera. Written by Nick Smith

If you stroll down the River Thames in central London and look almost directly south from the Embankment tube station, you’ll see a monument to Sir Joseph Bazalgette ‘engineer of the London main drainage system and of this embankment.’ Above the bronze bust set into a classical façade, a Latin inscription reads: FLVMINI VINCVLA POSVIT, or ‘he put the river in chains.’ In doing so, the great 19th century civil engineer transformed the health prospects of London’s rapidly expanding population of 2.5 million. Bazalgette is known today as the man who built the city’s first modern interconnected sewer network that was to do more than any other public project to wipe out cholera in London and is still in use today.


The memorial was unveiled in 1901, the last year of Victoria’s reign and a decade after Bazalgette’s death. As Chief Engineer of London’s Metropolitan Board of Works he had created a sewer system supporting most of the capital, that had improved public health to the degree that, according to the City of Westminster archives: “the Thames finally lost its reputation as the most polluted river in the world. Today, it is considered one of the cleanest metropolitan rivers and cases of cholera have not been reported in London since the late 1860s.” While perhaps not so well known to the public as other British engineers such as Brunel, Stephenson or Telford, Bazalgette deserves his place in the upper echelons.

We’re only going to do this once and there’s always the unforeseen

Joseph Bazalgette

Not much is known about Bazalgette’s early years other than he was born on 28th March 1819 in the London Borough of Enfield. Descended from wealthy French Protestant immigrants and the son of a Royal Navy captain who was wounded during the Napoleonic Wars, so little is known of Bazalgette’s early life and career that reputable sources such as the Encyclopaedia Britannica are often confined to brief summary statements such as: “Bazalgette in 1842 became a consulting engineer at Westminster.” And until he joined the London Metropolitan Commission of Sewers that was in charge of London’s daunting sewage problem, all we really know for certain is that his engineering career began in 1836 under the tutelage of the eminent Irish civil engineer Sir John Macneill, working on land drainage works in Northern Ireland. As an informed conjecture, because he lived and worked in the capital, we can also reasonably assume that the cholera epidemic that started in 1831 with the infection of keelman William Sproat, would have been known to the youngster.

By the mid-1850s London’s population was growing so fast that it had more than doubled in half a century (Bazalgette himself had 11 children). This unplanned urban growth created a vast increase in human waste that was to overwhelm a drainage system that had hardly evolved since Roman times. As a result, sewage contaminated the Thames which, despite being so polluted that it couldn’t sustain any wildlife, was for many a source of drinking water, meaning that the water-borne contagion spread like wildfire. As the disease took hold, infant mortality reached 20 percent, while life expectancy dropped to below 30 years. The Metropolitan Commission of Sewers reacted by issuing an order to close London’s cesspits, while domestic drains were to be connected to the sewers that emptied into the river. It was a move that only made matters worse, with the 1849-9 outbreak killing 14,137 Londoners.

By 1852, with the backing of Isambard Kingdom Brunel, Bazalgette took over the post of Chief Engineer of the commission after his predecessor had died from ‘harassing fatigues and anxieties’. Whether by accident or design, Bazalgette was now a main player in the fight against the capital’s massive waves of contagious diseases that apart from cholera included typhoid and influenza. How cholera was transmitted was not correctly understood at the time, with contemporary opinion holding that the disease was caused by foul air, the so-called ‘miasma theory’. It was English physician and miasma-skeptic Dr John Snow that posited the disease was waterborne, and his geographical study of instances of cholera in London is seen as the founding event of epidemiology. Although Snow’s analysis was not widely accepted at the time, the idea of containing the miasma in sewers had the unintended consequence of providing an escape route for the contaminated water that was actually causing the disease.

Image from The Engineer (June 1858) showing Bazalgette's London sewer plans

Meanwhile, technology tried to intervene in the form of first industrially mass-produced flush toilet that made its appearance in London in the 1850s. But with only one toilet per hundred people, and with their contents inevitably emptying into the river, the innovation initially had less of a positive impact on public health than it is usually given credit for. Soon the stench from the river was so foul that in 1858, during the so-called ‘Great Stink’, Parliament discussed relocating to either Oxford or St Albans, while the curtains on the river side of the Palace of Westminster were soaked in lime chloride to disguise a smell that, according to Charles Dickens, was of “a most head-and-stomach-distending nature.” In more journalistic tones, a leading article in the City Press newspaper railed: “­It stinks, and whoso once inhales the stink can never forget it and can count himself lucky if he lives to remember it.”

Read The Engineer's archive coverage of Bazalgette's proposals

Archive coverage of the Abbey Mills Pumping Station

More late great engineers

Having seen and smelled for itself the public health hazard created by London’s woefully inadequate drainage system, a reluctant government was galvanised into action and in 1858, despite the colossal expense associated with the project (about £1bn in today’s money), passed an enabling act that would allow proposals drawn up by Bazalgette to be put into practice. His solution was to build an extensive underground sewer network that diverted London’s waste downstream to the Thames Estuary – away from the main areas where people lived. To do this he proposed a ‘Main Drainage’ system of enclosed underground brick-lined main sewers to intercept sewage outflows from more than a thousand miles of street sewers that in turn intercepted the household raw sewage that ran unchecked in the streets. With the aid of four pumping stations the outflow was taken downstream to Erith Marshes, where it was stored in tanks to await discharge untreated into the Thames on the ebb tide. This huge scheme required the construction of 1,300 miles of sewers, 82 miles of intercepting sewers and the use of 320 million bricks. Throughout, the project Bazalgette specified Portland Cement, the first time that this new material had been used so extensively.

According to the Institution of Civil Engineers (of which Bazalgette was to become president in 1884) the genius of the scheme was matched in no small part by the engineer’s foresight in assessing the diameter of the pipes required. Basing his calculations on the most densely populated areas of the metropolis (and allowing each citizen a generous intake of food), he came up with a number and doubled it, saying: “We’re only going to do this once and there’s always the unforeseen.” This foresight meant that a century later the system still had the capacity to accommodate the mushrooming of London’s population created by the advent of the mid 1950’s residential tower block ‘building boom’. Says the ICE: “If Bazalgette had used the smaller pipe diameter, the city’s sewers would have overflowed in the 1960s. Instead, they’ve coped into the 21st century.”

Engineering drawing of the Abbey Mills pumping station from The Engineer

Alongside the Main Drainage, Bazalgette undertook the construction of the three Thames Embankments – Victoria, Albert and Chelsea – designed to constrict the river and reclaim land. In the case of the larger Victoria Embankment, the northern outfall sewer was incorporated into it along with the Metropolitan District Railway. In an effort to improve traffic flows in London, Bazalgette supervised the freeing of its tolls on twelve Thames bridges, designed replacement structures for three others (Putney, Hammersmith and Battersea) and supervised plans for some 3,000 new streets. In more than thirty years of engineering work, Bazalgette’s effect on everyday life in the metropolis was incalculable.

By the time of Bazalgette’s death in 1891, London’s population had redoubled and was standing at well over five million, while cholera had been relegated to merely a bad memory thanks to Bazalgette’s system for removing human waste from the city, even if only be a short distance. But the eight miles to Erith Marshes was crucial for London’s public health, and justified Bazalgette’s deceptively simple statement that the fundamental principle of the sewer system was one “of diverting the cause of the mischief to a locality where it can do no mischief.” Which brings to mind the achievements of the Bazalgette’s great-great-grandson, TV executive Sir Peter, that include importing the reality show Big Brother to British television screens, leading to the joke that while the Victorian engineer had consecrated his life to pumping it out of our homes, his descendant had dedicated his to reversing the process.