Well done on taking that advice at Bosworth and best wishes for your journey. Few are fortunate to have water needing no more than a couple of teaspoons of brewing salts and a particular recipe to brew a high class beer and from what I hear of water in your region, that is unlikely in your case.
Minerals in water are low enough to be quantified in parts per million, yet even small variations can have significant influences on beers. It is not difficult to alter the amounts of these components provided
you know what is there to start. A water test (
) overcomes this major obstacle and the Salifert kit lets you monitor your adjustments to alkalinity and also to some degree, monitor the variability or otherwise of your supply.
Water treatment is not complicated, but is confusing for many reasons including having single terms for what to a brewer are several different properties, like hardness. If 2.5g of calcium carbonate (chalk) were dissolved in 25 litres of deionised water (it won't but can be made to with CO2) it's hardness could be said to be 100mg/l CaCO3 or 100ppm CaCO3. The same hardness would apply if 4.3g of gypsum was instead dissolved in 25 litres and the same again with 6.15g of Epsom salts. (I think my sums are near enough right, but if they are not you might still understand my thrust.) The brewer doesn't need to know hardness, but instead that the first has 40ppm calcium and 100ppm alkalinity, the second similarly 40ppm calcium but with zero alkalinity and the third containing no calcium or alkalinity at all. For totally different reasons all three are unsuitable for brewing if untreated, yet with simple and low cost additions, all could be used to make good beer. Once you get your water report you'll forget about the likes of hardness when all else starts to fall in place.
Starting with water of unknown alkalinity can easily lead one to assume commercial brews won't be bettered using basic equipment in a kitchen or garage right up to applying the change that proves it not so. It is difficult to exchange sound detailed advice on water treatment made impossible when initial mineral contents aren't known. The recipient will often chase their tail in those circumstances and also if they have yet to perfect their other processes.
Mineral levels have a substatial impact on the chemistry influencing product quality as well as the flavours produced, so as we each have preferences the consumer can prefer a faulty version of their favourite type to a better quality version of another. The same can apply to some calculators when their developer would appear to find a profile not to their liking and advise against it. There are only a few important rules to learn, mainly to do with levels of alkalinity and calcium after which there is a very large field of open play meaning there can be very few waters that can't be used to make very good beers and they generally exist outside the UK.