Question:
I know some people use a Brita water filter. Where I am, there are two kinds being sold: a narrow one with a 'memory' on top recording when the filter needs changing, and a traditional wide one with no chip. I know Ken Wilson recently said the electronic memory system was not necessary (although I like the narrow jug, and the firm doesn't seem to give a choice of jug shape). I read on the filter refill box that you have to use a new filter once a month and you must use one lot of filtered water up within two days. I don't know if I'd always use up that water in two days, although it's obviously more profitable for Brita if I do. If I kept the water cold, why should I throw it out after 48 hours?

Any other comments would be welcome too. I've been using a coffee maker with built-in filter, but I'm thinking of getting a real machine and thinking of using a water filter with it.

Answer: Presumably, Margaret is starting with ordinary tap water. Such water (at least in the US) is unlikely to have high bacterial counts to begin with. Milk, eggs and other products much more prone to spoilage than water (and more likely to be contaminated with coliform- cows and chickens are not the world's cleanest animals) are pasteurized by briefly heating to 160. Cooking these products at a rolling boil for 5 minutes would make them inedible. I suspect your health dept. is erring on the side of caution in the case of water suspected to be contaminated with raw sewage, figuring that the extra boiling won't hurt.

Please see this web page for more details: http://www.accessone.com/~sbcn/metcalf.htm

The bottom line is that 66C (150F) is all you need to make water safe. This makes sense in that infectious microbes which harm humans are meant to live at body temp (99F), so 150 is well beyond the temperature conditions in which they are evolved for. The 5 minute boil is basically an old wives tale and may discourage people in poor countries for whom fuel is precious from pasteurizing at all. This would not be the first nor the last time that a government agency gave you bad advice.