Originally Posted by gbx
I have a decent science background (did chemistry my first 2 years of university) and a lot of what I read in books doesn't sit right with me. They all have the same or similar classic cities water profiles but the citation is other brewing books, never a city of london water report. It seems like a nice little story about water and the influence of beer styles but a lot of the story doesn't make sense - eg. they talk about the london water and bitters but london brewers burtonized their water for pale ales so their starting water is irrelevant.
I had the same concern. There is a great daisy chain of circular references regarding water profiles. Who knows where some of them came from. That's why I did the research into a bunch of the water profiles from many historic brewing centers. The water profiles in Bru'n Water represent the best information I could assimilate.
I researched current water reports from most of those cities along with research on what the water source IS and WAS. In addition, I evaluated if the current water is treated in a manner other than filtration and disinfection. Those processes do not alter the water profile, but processes like lime softening, ion exchange softening, or membrane softening do alter the profile. Fortunately, none of these historic centers perform that sort of treatment.
The other concern was the altering of the source of water supply in the cities. That took a little digging to ascertain where they used to get their water when their reference styles were created. There were a lot a places where the sources have not changed.
London is one of those places where there are multiple sources. Thames Water Authority runs a decentralized water system in London and there are wells all over the place and the water quality varies moderately by location. Deciphering what a London profile might have been is difficult, but I've looked at a sampling of the central London current water quality and estimated a ionically-balanced profile for that location. I would not assume that all London brewers Burtonized their water prior to brewing. There are plenty of English styles that would not benefit from Burtonizing, so that should not be an initial assumption for London water. In the case of brewing a Pale Ale in London, assuming Burtonizing is probably a safer bet. In any case, that London profile in Bru'n Water should be a pretty good estimate of what the conditions may have been.