Using Water Profile for Brewing

Rick, water chemistry can indeed be confusing. I think one of the reasons that the topic is so frustrating to read about is partly due to the number of different units that are used to express the concentration of ions in water. The analysis you sent from Ward Laboratories is typical of modern water lab reports and provides the concentration of the specific ions of interest, versus “lumpy values” like total alkalinity as CaCO₃.

Another reason that water chemistry is confusing to read about is because folks who write about water want to explain other stuff along with providing practical and easy to use information; the resultant works are often trying to digest. I am guilty of this and want to take another crack at this topic in an attempt to convert the values in your water analysis into something you can use.

To begin with, most of what is provided in a water analysis can be ignored for the first step used to evaluate water for brewing. The critical ions are calcium (Ca⁺²), magnesium (Mg⁺²), bicarbonate (HCO₃^–), and carbonate (CO₃^-2) because these affect mash and wort pH. The practical brewer wants to know some specifics about how different waters will affect pH, not just that some effect is going to occur.

To answer this question, we are going to use a simple calculation table that is loosely patterned on a currency conversion table. Think of this process as converting four different currencies into one so that we know how much beer we can buy at the local pub . . . or something like that!

Step 1 – Fill in the blanks in Table 1 with what is known about your water (the colors in the table are used to categorize the information).
Step 2 – Do the math that the table instructs.
Step 3 – Total up the values to approximate how mash pH will be influenced by the water.

So, what does this table do and what does it tell us about your water? For starters, this is a conversion table that converts the concentrations of the ions in water that go on to influence mash pH directly into a variant known as degrees German Hardness (˚dH) that can be added together to predict how mash pH will be altered using this water instead of distilled water (this is a digested form of residual alkalinity calculations). The nice thing about Table 1 is that the messiness of water chemistry is totally skipped. This table may be helpful if you want to see how your water compares to a few examples.

In the number crunching shown here, the prediction is that your mash pH is going to pushed up by 0.2 pH units compared to brewing the same beer with mineral-free or distilled water. The +0.2 value means that for most beers, your water needs some acid balance, either by directly adding acid, acidulated malt, or acidic specialty malts. Another approach is to remove some of the bicarbonate by boiling. These adjustments are really outside of the scope of your question, so I will leave adjustment for the time being.
OK, we have answered the mash pH question; we know your water has residual alkalinity that is going to push mash pH upwards and you have some remediation options that we will circle back on later. What about flavor ions? The biggies are: Magnesium, sodium, chloride, and sulfate. Brewing waters are really all over the place with these ions and there is no right answer when it comes to flavor ions. Depending on the style of beer you are brewing, chloride and sulfate concentrations, as well as the ratio of the two, are something to consider. Chloride is generally associated with a softer, “sweeter” water and sulfate is considered to be a more aggressive mineral water that accentuates dryness and bitterness. My preference is a combination of the two. I also like some sodium in my water as long as it does not lend salty flavors to beer because sodium rounds out the palate; for whatever reason, much of the information about brewing water tends to gloss over sodium.

Magnesium is the one flavor ion (also a pH ion) that may raise a hairy eyebrow, or two, with your water. Although magnesium pushes mash pH downward, which is generally viewed as positive, it can add bitter and metallic flavors when concentrations exceed about 50 ppm. While magnesium values reported in the literature vary by style, the takeaway is that this is an ion that has the potential to drive beer flavor onto unwanted paths. Your water is high in magnesium, plain and simple, and the flavor of magnesium is unmistakable. In some English ales, it does add a very interesting and enjoyable flavor layer when the levels are not extreme, but in other styles magnesium can simply add a distracting and unpleasant flavor note.

I have never been a huge fan of looking at textbook values for classic brewing waters by style and city because much of this information lacks context. Take Munich for example. The water in Munich is well-suited for brewing dark lagers because its chemistry pushes mash pH up, balancing the malt grist used to brew darker beers. But what about all of the great helles lagers and weizen beers brewed in and around Munich? Well, Paul Kolbach did develop the concept of residual alkalinity to help brewers tailor local brewing waters to beer type in the early 1950s and German brewers certainly have not been blind to water chemistry. In other words, textbook water values of traditional brewing centers may or may not describe the actual water used for brewing.

What are the takeaways from this brief jump into the cloudy pool of water? Here are some bullets that may be helpful:

Start your water review by considering how your water’s composition will affect mash pH because that is really the foundation of this entire topic.
Does your water have anything that may have a detrimental effect on beer flavor?

If you want to use local water and the analysis from the points above don’t suggest alignment of the brewing stars, there are a few things you can do to mitigate the issues. You can dilute your water with RO or distilled water to minimize the concentrations of things that may be problematic, for example magnesium. However, water dilution does not change the alkalinity balance.

Adding more calcium to your water can balance the alkalinity, however, you may be moving into a water profile that is not well-suited for a diverse selection of beers.

Response by Ashton Lewis.