Source:  Snow, John. Med. Times and Gazette, n. s. vol. 9, Sept. 2, 1854, pp. 247-248.

Communication of cholera by Thames water

To the Editor of the Medical Times and Gazette.

Sir,--I have been engaged, during the last ten days, in an inquiry which promises to yield very conclusive evidence respecting the mode of propagation of cholera. You are, no doubt, aware, that there is an Act of Parliament requiring those Water Companies of the Metropolis which obtain their supply from the River Thames, to procure it at some point above the reach of the tide, and, consequently, free from the sewage of London. A certain time, which is not yet expired, was, however, allowed for the completion of the necessary works. The Lambeth Water Company, which formerly obtained their supply from a point near Hungerford Suspension-bridge, completed their works at Thames Ditton [near Hampton Court Palace] upwards of a year ago, and have ever since distributed water perfectly free from the sewage of London. The Southwark and Vauxhall Water Company, which, along with that just named, supplies the greater number of houses on the south side of the Thames, still obtain their supply from Battersea-fields, near Vauxhall. The mortality from cholera was much less during the epidemic of last autumn, in the districts to which the new supply of water extended, than in those districts which are exclusively supplied by the Southwark and Vauxhall Company. This will be seen on referring to a table in the return of deaths in London, for the week ending the 26th of November, 1853. Soon after the commencement of the present epidemic, the difference in the mortality of the respective sets of districts was equally apparent,--a difference which did not exist in 1849.

In order to ascertain clearly on what this difference in mortality depended, it was necessary to make an inquiry in detail. The only districts which are supplied exclusively with the water from Thames Ditton, are such distant places as Balham, Streatham, Dulwich, and Sydenham, whose freedom from the epidemic might be attributed to other causes than the mere absence of the polluted water. In the districts of Lambeth, Newington, and St. George, Southwark, the customers of the two Companies are so intimately mixed with each other, that two adjoining houses have very often a different supply of water; and it was, therefore, impossible to determine what kind of water was used in the houses in which the deaths from cholera occurred, except by an inquiry on the spot. I consequently resolved to call at each house where there had been a death from cholera; and Mr. Farr has been kind enough to allow me to take a copy of the addresses of those cases which have not been published in the weekly returns. I have gone over the sub-districts of Lambeth, called Kennington, first part, and Kennington, second part, as regards the deaths from cholera which occurred down to August 12; and the sub-districts, Waterloo, first part, and Waterloo, second part, to August 19th. The following are the results I have obtained:--

Kennington, First Part

Supply

No. of Houses

Southwark and Vauxhall

27

Lambeth

2

Pump-wells on premises

2

 

Total 31

 

Kennington, Second Part

Supply

No. of Houses

Southwark and Vauxhall

11

Lambeth

2

 

Total 13

 

Waterloo, First Part

Supply

No. of Houses

Southwark and Vauxhall

7

Lambeth

1

Not yet ascertained

1

 

Total 9

 

In Waterloo, second part, 27 deaths have occurred in 24 houses, which are supplied as follow: -

 

No. of Houses

Southward and Vauxhall

17

Lambeth

3

Pump well close to the Thames; water dirty

1

Wells at the Lion Brewery

1

Not yet ascertained

2

 

Total 24

 

If the cases are enumerated instead of the houses in this last sub-district, the return is as follows: -

supply

No. of Houses

Southward and Vauxhall

19

Lambeth

3

Pump wells

3

Not yet ascertained

2

 

Total 27

According to the returns made by the water companies to Parliament and to the Board of Health, there are quite as many houses supplied by the Lambeth as by the Southwark and Vauxhall Company, in the above districts; and both Companies supply alike all kinds of houses,--those of the rich and the poor indiscriminately. It is evident, therefore, that, in the sub-districts to which the inquiry has extended, the people having the improved water supply enjoy as much immunity from cholera as if they were living at a higher level, on the north side of the Thames; and I ascertained that in two of the instances where the water supply afterwards turned out to be of the improved kind, the cases could be traced to personal communication with previous ones.

I intend to continue the inquiry, extending it to the other sub-districts in which the two water companies are intermixed, and to bring it down to the 26th inst. After this date, I am informed by Mr. Farr that the supply of water at the house in which every fatal attack of cholera may occur, will be returned by the Registrars in all the Districts on the South of the Thames. An amount of information will thus be obtained that will be very conclusive. In the mean time, I have considered that the inquiry, even in its present stage, is too im-[247/248]portant to be withheld from the Profession, at a season when every week is adding so much to the mortality from cholera.

I must say a word on the nature of the water supplied by the Southwark and Vauxhall Company. It is not worse, either physically or chemically, than the water that has generally been supplied to town populations. It undergoes a coarse kind of filtration before it is distributed, and it passes with careless observers for being quite clear, though it is not so in reality. It contains organic matter, both in solution and suspension, and deposits a small quantity of whitish flocculent matter on standing. It also contains a much larger quantity of chlorides than Thames water obtained above the reach of the London sewage. As the Chelsea Water Company obtain their supply from almost the same part of the Thames, and have in every epidemic very much less cholera in their district, I may as well explain, that they filter their water much better than the Southwark and Vauxhall Company, and no doubt rid it to a much greater extent of the cholera evacuations which pass down the sewers into the Thames. I am, etc.

18, Sackville-street, Aug., 1854.

John Snow

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