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
Variant Creutzfeldt–Jakob disease Variant Creutzfeldt–Jakob disease Variant Creutzfeldt–Jakob disease (vCJD) is a type of brain disease within the transmissible spongiform encephalopathy family. Symptoms include psychiatric problems, behavioral changes, and painful sensations. The length of time between exposure and the development of symptoms is unclear, but is believed to be years. Average life expectancy following the onset of symptoms is 13 months. It is caused by prions, which are mis-folded proteins. Spread is believed to be primarily due to eating bovine spongiform encephalopathy (BSE)-infected beef. Infection is also believed to require a specific genetic susceptibility. Spread may potentially also occur via blood products or