A boil-water advisory, boil-water notice, boil-water warning, boil-water order, or boil order is a public-health advisory or directive issued by governmental or other health authorities to consumers when a community's drinking water is or could be contaminated by pathogens. Under a boil-water advisory (BWA), the Centers for Disease Control and Prevention recommends that water be brought to a rolling boil for one minute before it is consumed in order to kill protozoa, bacteria, and viruses. At altitudes above , boiling should be extended to 3 minutes, as the lower

boiling point The boiling point of a substance is the temperature at which the vapor pressure of a liquid equals the pressure surrounding the liquid and the liquid changes into a vapor. The boiling point of a liquid varies depending upon the surrounding envir ...

at high altitudes requires more time to kill such organisms. BWAs are typically issued when monitoring of water being served to consumers detects ''

E. coli ''Escherichia coli'' (),Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. also known as ''E. coli'' (), is a Gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus ''Escher ...

'' or other microbiological indicators of sewage contamination. Another reason for a BWA is a failure of distribution system integrity evidenced by a loss of system pressure. While loss of pressure does not necessarily mean the water has been contaminated, it does mean that pathogens may be able to enter the piped-water system and thus be carried to consumers. In the United States, this has been defined as a drop below .

History

John Snow John Snow (15 March 1813 – 16 June 1858) was an English physician and a leader in the development of anaesthesia and medical hygiene. He is considered one of the founders of modern epidemiology, in part because of his work in tracing the so ...

's 1849 recommendation that water be "filtered and boiled before it is used" is one of the first practical applications of the germ theory of disease in the area of public health and is the antecedent to the modern boil water advisory. Snow demonstrated a clear understanding of germ theory in his writings. He first published his theory in an 1849 essay ''On the Mode of Communication of Cholera'', in which he correctly suggested that the fecal-oral route was the mode of communication, and that the disease replicated itself in the lower intestines. Snow later went so far as to accurately propose in his 1855 edition of the work that the structure of cholera was that of a cell. Snow's ideas were not fully accepted until years after his death in 1858. The first known modern boil-water advisory based solely on

germ theory The germ theory of disease is the currently accepted scientific theory for many diseases. It states that microorganisms known as pathogens or "germs" can lead to disease. These small organisms, too small to be seen without magnification, invade ...

and unfettered by extraneous and irrelevant advice was distributed in 1866 during the last of three major cholera outbreaks that ravaged London in the 19th century.

References

{{watersupply-stub Drinking water Health campaigns Water treatment

History

See also

References