The role of water in the transmission of disease

Discovered by sewer workers investigating a blockage in Whitechapel, this behemoth was over 250 metres long and weighed an estimated 130 tonnes. Composed of congealed oil and fat, saponified in the alkaline sewer environment, and studded with a distasteful potpourri of grit, faeces, wet wipes and other objects discarded into the system, fatbergs can sometimes have the consistency of concrete. They are a relatively recent phenomenon reflecting increased population and changing habits since the sewerage system was first built in the 1860s and something never envisaged by its builders. 

The recent discovery did, however, serve to remind Londoners of the masterpiece of Victorian civil engineering beneath their feet. Its architect, Joseph Bazalgette, Chief Engineer of the Metropolitan Board of Works, has already received brief mention in the very first of these London Microbiota pieces, but given his contribution to ridding the city of epidemic typhoid and cholera he warrants more. Sadly his only public memorial, apart from his works, is a small plaque on the Victoria Embankment (itself built to house one of his main sewers). 

Prior to Bazalgette’s great work, most of London’s sewage flowed into the Thames. The capacity of the river to remove the sewage swiftly was impeded by the fact that the river is tidal all the way up to Teddington so at times of slower flow, particularly in the summer months, sewage would accumulate in the river, cruising up and down with the tide. Bazalgette’s solution was to prevent sewage flowing into the Thames with a series of intercepting sewers running roughly west to east: three north of the Thames and three south. Those north of the river meet in east London where it is necessary to pump sewage from the lower sewer up 11 metres (36 feet) so that it can continue to flow under gravity to Beckton and what is now the largest sewage treatment works in Europe. To do this, a pumping station was built at Abbey Mills in Stratford (one at Crossness serves a similar purpose south of the river). Though it now only operates as a standby, its original function having been assumed by a nearby, zinc-clad pumping station built in 1997, the magnificent Byzantine-style, listed building, is often described as the ‘Cathedral of Sewage’. 

For microbiologists, it also serves as a worthy monument to the vanquishing of the miasmatic theory of disease (put succinctly by Edwin Chadwick in evidence to a Parliamentary Committee in 1846 as ‘all smell is disease’). Though John Snow is justly credited with being instrumental in establishing the role of water in the transmission of disease, his ideas were not widely accepted at the time. The Board of Health set up a Committee of Scientific Enquiry into cholera, including notables such as: William Baly from St Bartholomew’s Hospital, who had previously dismissed Snow’s view in a report for the Royal College of Physicians; Richard Owen, later a noted antagonist of Charles Darwin; William Farr, a statistician from the Registrar General’s Office; and John Simon, Medical Officer for the City of London. They reviewed Snow’s evidence for the waterborne nature of cholera and concluded, ‘After careful enquiry we see no reason to adopt this belief’. 

However, in 1866, with work on the sewage system well under way, an outbreak occurred in east London, which marked a significant change in the prevailing view. Water supplied by the East London Water Company was heavily implicated and former members of the Committee had begun to doubt their earlier conclusions. The water company was robust in its defence, their Chief Engineer writing to the Times pointing out how all of its water was protected from contamination and filtered, a claim brought into doubt when William Farr visited the locality and met two customers who claimed to have found eels blocking their water pipes. Farr wrote to Bazalgette, who replied that the outbreak occurred in a place where his works were still not complete. In particular, the Abbey Mills Pumping station would not be operational until the following summer. He promised to install temporary measures to ensure the sewage was pumped up to the Northern outfall – too late for the estimated 4,000 people in the area who died in July and August that year. Farr was convinced of its source and, like many others, highly critical of the water company. He bitterly ascribed the persistence of miasmatism to the convenience of blaming airborne contamination since air, unlike water, was not supplied by commercial companies. 

Bazalgette, unwilling to venture beyond his own area of considerable expertise, restricted himself to saying at a meeting of Civil Engineers, ‘Although great differences of opinion existed and continue to exist as to the cause of the disease… the places formerly most favourable to the spread of disease became quite free from it, when afterwards properly drained.’ 

Farr’s colleague on the earlier enquiry, John Simon, followed, reporting to the Privy Council in 1870, ‘it [is] now certain that the faulty water supply of a town may be the essential cause of the most terrible epidemic outbreaks of cholera, typhoid fever, dysentery and other allied disorders.’ Abbey Mills thereby assumes a symbolic status comparable to the Broad Street pump handle in the history of applied microbiology and public health. 

Not usually open to the public, few tourists visit Abbey Mills now, particularly if you exclude those misguided individuals who arrive at Abbey Road DLR Station looking for the Beatles’ recording studios. As for the Whitechapel fatberg, it has now been cleared. A small piece was partially dried for display in the Museum of London, where the possibility that fly larvae encased within might hatch promises to make it the museum exhibit that just keeps on giving.