Water chemistry is the ingredient homebrewers ignore longest and regret ignoring soonest. The same grain bill and hop schedule can taste sharp and dry or round and malty almost entirely because of the calcium, sulfate and chloride dissolved in the water it was mashed and sparged with — and a handful of famous beer styles exist specifically because a region's water pushed brewers toward one flavour direction long before anyone understood the chemistry behind it.
Every profile here gives the classic reference figures for calcium, magnesium, sodium, sulfate, chloride and bicarbonate in parts per million, aggregated from commonly published brewing-water references, alongside a short note on why that water shaped the style it's associated with. Burton-on-Trent's famously sulfate-loaded water is the reason English pale ale developed a sharp, dry, hop-forward character; Pilsen's extremely soft water is the reason Pilsner could be brewed pale, delicately hopped and still balanced, because there was no mineral hardness pushing back against a heavier hop rate; Dublin's moderate hardness with high bicarbonate relative to calcium suits the roasted, slightly acidic character of a dry stout almost perfectly.
These are historical reference approximations, not a live feed of what's actually coming out of any tap today — municipal water treatment changes over years and decades, and the exact numbers published for "Burton water" in a homebrew text are a convenient, standardised approximation, not a certificate of analysis from last week. If you're trying to build a specific water profile for a real batch, start by testing your own source water (a Ward Labs report or similar) rather than assuming any of these figures apply to what's coming out of your own tap, then use these profiles as a target to build toward with brewing salts.
The two most commonly adjusted salts are gypsum (calcium sulfate), which pushes toward a drier, sharper perceived bitterness, and calcium chloride, which pushes toward a fuller, rounder, maltier mouthfeel — the classic move for balancing a very sulfate-forward water when brewing something malt-focused.
Every profile page also links back to the style it's most associated with, so you can see the water-chemistry side of a style's character alongside its grain bill and hop schedule, rather than treating water as an afterthought once the rest of the recipe is already set.