Most brewers know that beer is comprised of somewhere between 90–95% water. So it makes sense that the water you are using can have a major impact on the beer. In the best case, the water profile can enhance and lift the beer and its body and mouthfeel. In the worst case, it can leave the brewer with a beer tasting similar to chewing on a Band-Aid and smelling like hot plastic. Water treatments don’t need to be complicated, especially if you can start with reverse osmosis (RO) water. But even without RO, some easy tricks should produce a fine beer.
Tap vs. Reverse Osmosis
On my first trip to Florida, I poured a cup of tap water when I arrived at the condo we were staying . . . only to quickly spit it out. To me it was undrinkable . . . it was like drinking a sulfur stew. If that at all describes your water, then RO water is highly recommended. Also, if you’re in a location that deals with very hard water, high iron, or other total dissolved solids, then RO water would also be recommended. Why? Because what the reverse osmosis process does is strip the water of the dissolved solids that can possibly wreck havoc on your beer. If purchasing an RO system is out of your reach currently, purchasing 5-gallon (19-L) jugs of water at your grocery store is another option.
For folks that are on a municipal water supply, tap water may present itself as nearly undrinkable due to the chlorination process many water departments add to the supply. But chlorines are one of the easiest compounds to treat when it comes to brewing. Campden tablets (sodium metabisulfite) are what I consider the easiest way to treat both chlorine and chloramines found in your water supply. One crushed tablet added to your brewing water will treat up to 20 gallons (76 L). Half a tablet is good for a 5-gallon (19-L) batch size. Adding a little too much is not a bad thing. I used to treat the water the night before brew day but I have since learned that is unnecessary as the metabisulfite acts quickly. Adding while the strike water is warming up is all that is needed.
Carbon block filtration is another way to treat chlorinated municipal water. This is a little more costly and filters need to be replaced regularly. Also, carbon block filters do need time to properly treat the chloramines so a slow fill is recommended when using this type of setup.
For brewers using tap water, obtaining a water report from municipal town/city water departments is recommended for those that have them available. You may need to send water samples away to an agricultural or other water analysis laboratory if they aren’t available or if you are using well water. Once you have a water report in hand, it gets easier to burrow down into the details of how to adjust your specific water.
Folks utilizing RO, or very soft water that is low in total dissolved solids, start with a leg up since it is the easiest water to work with in a brewery. It’s like trying to paint your masterpiece with a blank canvas versus one where Jackson Pollack had already applied a few strokes. First off, there is a big difference here between all-grain brewers and brewers utilizing extracts. Please note that extracts already have salts in them and generally I don’t add more unless it is truly desired.
There are several salts that we can utilize to affect the flavor of the beer, typically calcium chloride and calcium sulfate (gypsum) are the two most widely utilized. But there are others that can be utilized to provide balance or lift to the beer: Calcium carbonate, magnesium sulfate (Epsom), and sodium chloride (table salt) are most commonly used and easy to obtain. One of the best ways to get a sense of how they can impact beer is by experimenting on your own. Get some distilled or RO water and start sprinkling the salts and taste. See how each impacts the mouthfeel and taste of the water. Then try it again on beer, either a homebrew or commercially available one. Just be careful of foaming with carbonated beers when you sprinkle, as the salt will provide nucleation sites for the carbon dioxide to come out of solution.
How much salt to add is going to be tricky as it depends on your water profile and your desired goal with the beer. If using tap water, you will need to take the starting level of each dissolved ion from the various salts into account before making any additions. This is where the water report is essential.
This is a complex topic and for the sake of brevity, I will say that utilizing RO water will almost always be the best solution. If you are dealing with hard water, lactic or phosphoric acid may be your best friend. Whether working with tap water or RO, for more in-depth coverage on this topic, I’ll refer to you to the following article: https://byo.com/article/understanding-residual-alkalinity-ph/
To wrap things up, I want to add that if you are using RO or very soft water low in dissolved solids, Gordon Strong did an excellent dive into the topic found in the March-April 2020 issue (or at https://byo.com/article/brewing-with-reverse-osmosis-water/). He covers several different beer styles and how to build up the mineral profile to match the style.