[eadmund]

> I always thought it quite weird that somehow by virtue of being in beer, that the water somehow becomes sterilised.

The reason that water in beer is sterilised is that beer is brewed — i.e. boiled.

> If you've ever tried home brewing, you'll know that non-sterile conditions lead to foul rancid filth due to all the bacteria etc.

I believe that pre–germ-theory brewing practices tended to discourage unwanted microbial activity, in part through inoculation with large amounts of fresh barm. Did they put two and two together and connect those practices in the context of brewing to the broader context of water or food safety? Maybe.

> I'd find it odd if the people then knew to sterilise the water and equipment to make beer, but then not do the same to drink it.

Indeed, the article quotes Paulus: ‘But waters which contain impurities, have a fetid smell, or any bad quality, may be so improved by boiling as to be fit to be drunk.’

[IAmBroom]

Again, beer isn't boiled - as long as we're quashing myths here. It is heated.

[eadmund]

> Again, beer isn't boiled - as long as we're quashing myths here. It is heated.

I think that you are confused. Mashing is used to convert the starches in malted barley into sugars, and is done at temperatures below under boiling (well, with decoction mashes a portion of the mash is boiled, but the mash as a whole is not). But then the sweet wort produced from mashing is pulled off, hops are added and the wort is — yes — boiled, typically for quite awhile, and generally quite vigourously. Then the wort is chilled, yeast is pitched in and it ferments.

The brewing process most definitely involves boiling in every beer style I am aware of. It’s definitely possible that there is some style out there which doesn’t do it, of course, but the vast, vast majority are.