Nice one Smarty - with the name Dr. Howard Backer I found this link:-
Water Disinfection for International and Wilderness Traveler
Howard Backer
Division of Communicable Disease Control, California Department of Health Services, Berkeley
http://www.journals.uchicago.edu/CID/journal/issues/v34n3/010954/010954.html
Here's an extract:-
Heat
Heat is the oldest means of disinfecting water. The advantages and disadvantages of using heat for water disinfection are as follows:
Heat neither imparts additional taste to nor improves the taste, smell, or appearance of poor-quality water.
Heat is a single-step process that inactivates all enteric pathogens.
Heat's efficacy is not compromised by contaminants or particles in the water, as is the case with halogenation and filtration
Fuel sources may be scarce, expensive, or unavailable.
Heat inactivation of microorganisms is exponential and follows the rules of first-order kinetics [24]. Thus, thermal death is reached in less time when higher temperatures are used; lower temperatures are effective when a longer contact time is used. Pasteurization uses this principle to kill enteric food pathogens and spoiling organisms at temperatures of 60°C70°C, temperatures that are well below the boiling point [25]. All common enteric pathogens are readily inactivated by heat, although the heat sensitivity of microorganisms varies (table 2).
Table 2. Temperature and time required for heat inactivation of microorganisms.
Bacterial spores, such as Clostridium spores, are heat resistant (some can survive for long periods at a temperature of 100°C) and are ubiquitous in the natural environment, but they are not waterborne enteric pathogens [36]. Thus, sterilizationthe destruction or removal of all life formsis not necessary for drinking water.
Because enteric pathogens are killed within seconds by boiling water and are killed rapidly at temperatures >60°C, the traditional advice to boil water for 10 min to ensure potability is excessive. Because the time required to heat water from a temperature of 55°C to a boil works toward disinfection, any water that is brought to a boil should be adequately disinfected. Boiling water for 1 min or keeping water covered and then allowing it to cool slowly after boiling can add an extra margin of safety [37]. The boiling point decreases with increasing altitude, but this is not significant when compared with the time required to achieve thermal death at these temperatures.
Although heating water to boiling is not necessary, it is the only end point that can be easily recognized without use of a thermometer. The temperature of hot tap water and the temperature of water that is too hot to touch vary too widely to be reliable determinants of pasteurization of water [29, 31]; however, if no reliable method of water treatment is available, tap water that has been kept hot in a tank for some time (at an estimated temperature of 55°C60°C [140°F] for at least 30 min) is a reasonable alternative [38]. Travelers with access to electricity can boil water with the use of either a small electric heating coil or a lightweight electric beverage warmer brought from home. In austere or desperate situations, an adequate temperature for pasteurization can be achieved in hot, sunny climates by use of a solar oven or simple reflectors [39].
