No big surprise perhaps. We are water based life forms and live on a water based planet. We expect things to have water in them. H2O. All water is the same, so what is the big deal. Or is it?
Yes, in its purist form water is two parts Hydrogen and one part Oxygen. Yet we rarely find it in the purest form. Water coming from the ground has minerals in it. The tap water, with mineral presence has yet additional items in it to help keep it safe to drink, such as chlorine. Spring water, while clean and clear, is still often filtered and contains minerals. If you want pure H20, get a gallon of distilled water.
When it comes to making beer, water can be very important. Historical styles of beer taste the way the do, in large part because of the water chemistry in the region in which they were brewed. For some styles it will be important to mimic the water of that region of the world. John Palmer, in his book "How To Brew" talks about water in Chapter 4. Let's look at an excerpt from "Taste of Water".
Water is very important to beer. After all, beer is mostly water. Some waters are famous for brewing: the soft water of Pilsen, the hard water of Burton, Midlands, and pure Rocky Mtn. spring water. Each of these waters contributed to the production of a unique tasting beer. But what about your water? Can it make a good beer? When using malt extract, the answer is almost always "Yes". If you are brewing with grain, the answer can vary from "Sometimes" to "Absolutely".
This part of his book is focusing on brewing with Extract, but I find great solace in the fact that as long as the water tasted good, it will make good beer.The reason for the difference between the brewing methods is that the minerals in the water can affect the starch conversion of the mash, but once the sugars have been produced, the affect of water chemistry on the flavor of the beer is greatly reduced. When brewing with malt extract, if the water tastes good to begin with, the beer should taste good.
Remember, brewing can be as simple or as complicated as you wish. I know some people who start with distilled water and add various minerals to it, in an effort to precisely create water as found in certain areas of the world. Me? If I can run the tap water through a carbon filter, I've found it turns out well. In many instances I will add some Gypsum to it. This will help mimic the harder water of Burton on Trent, famous for the British ales.
Most of the time, I find myself purchasing gallons of spring water. Note that distilled is not a good choice, as the minerals are good for the mash.
I don't wish to get any deeper in this. For one reason, I don't know too much more. There are so many details to get involved in with the brewing process. Water and water chemistry are just not ones I've chosen to dive into (at least not yet). Keep it simple. Get filtered or spring water for brewing.
And happy brewing. But wait! We need to talk about hops next. Stay tuned for Part 3. While you wait, check out Part 1 (Barley) if you missed it or simply to read again.
*** I had a hard time finding a definitive answer on this, but sources I've found report more than 95%, and even up to 97%. It will naturally vary depending on the style and percent of alcohol present.