Water heating by a domestic water heater. Two conflicting safety issues affect water heater temperature—the risk of scalding from excessively hot water greater than , and the risk of incubating bacteria colonies, particularly "Legionella", in water that is not hot enough to kill them. Both risks are potentially life-threatening and are balanced by setting the water heater's thermostat to . The European Guidelines for Control and Prevention of Travel Associated Legionnaires’ Disease recommend that hot water should be stored at and distributed so that a temperature of at least and preferably is achieved within one minute at points of use. If there
Boil-water advisory Boil-water advisory A boil-water advisory or boil-water order is a public health advisory or directive given by government or 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 at high altitudes requires more time to kill such organisms. BWAs are typically