Northern_Brewer
British - apparently some US company stole my name
High TDS doesn't mean it's not potable, you're not going to get sick from having a lot of chalk in water for instance. It's pretty typical in southeast England to see CaCO3 equivalents alone being in the 250-300ppm range, and the other ions can easily add 100-150ppm - see eg Fuller's and Shepherd Neame's tapwater (hmm, can't link Shep's hardness but it's 287ppm on average). Some areas of Kent have 90% of their water from chalk aquifers - before they started mixing it with other sources there was so much bicarbonate in it that it used to come out cloudy and slightly pétillant out of the tap. You're not going to get sick from that - it's essentially the same stuff as some hangover cures(!) - but the TDS must be pretty high for that to happen.
No. Aside from the fact that there's no such style as ESB, that kind of chalky water is so unsuitable for English-style pale beers that the big London brewers would build whole new breweries 200 miles away in Burton, rather than brew pale beer with London water. It's only good for porter if anything. Once they learnt more about water chemistry they could treat it with lots of sulphuric/hydrochloric acid to reduce the alkalinity, and gypsum/calcium chloride to get the right anions.
