For most of brewing history, water has been ignored. It was wet, it dissolved the beery goodness from barley, and it quenched thirst. Any understanding was intuitive. Bad-tasting water made bad tasting beer. Too much iron, your beer tasted bloody. A crisp, pale lager in one town produced an insipid beer in another town. Dublin, London, and Munich's carbonate-rich water made perfect dark beers where Burton Upon Trent's sulfate-laden water provided extra hop punch to Pale Ales.

The impact of your water depends on its source and the conditions it traveled through to get to you. The combination of water source, time of year, and the state of your plumbing affects what you brew best.