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
Disease in colonial America to the country and very controversial because of the threat that the procedure itself could be fatal, or otherwise spread the disease. It was introduced by Zabdiel Boylston and Cotton Mather in Boston in 1721. The procedure involved injecting the infection into the patient, which resulted in a mild form of the disease. This led to a shorter period a person had Smallpox than if they had contracted naturally. Strong support for inoculation came the leading Puritan minister, Cotton Mather, who preached for inoculations during the 1721 smallpox epidemic in Boston. His advice was heeded primarily by well-educated wealthy Puritan