Water

Yes it is a whole book dedicated to the use of Water in brewing. I very much enjoyed the previous book in the series on Yeast which helped point me towards controlling fermentation temperature and BrewPi. By the time I've got to page 2 I find my approach and understanding of water treatment for brewing (boil it to remove temporary hardness and burtonise it with gypsum) is typical " of brewing textbooks from the later half of the twentieth century". So I clearly have a lot to learn in the twenty first century. But I will be sticking with my standard approach tomorrow when Adam comes round for a brew and hop picking day.