A boil-water advisory or boil-water order is a public health advisory or directive given by government or health authorities to communities when a community's drinking water is, or could be, contaminated by pathogens.[1]
Under a boil water advisory, it is recommended that water be boiled for several minutes in advance of consumption or use, in order to kill off as much of the bacteria and viral contamination as possible.[2]
A common cause is a loss of pressure due to a failure of distribution system integrity. While loss of pressure does not necessarily mean the water has been contaminated, it does mean that potential pathogenic materials in contact with water supply plumbing may be able to diffuse into the system and thus be carried to consumers. The normal pressure of the water supply system would prevent this inward diffusion, as any leaks would force contaminants away from the supply.