By Greig McGill
Well, I can’t put it off any more! The Brewshop.co.nz team has been asking me to write this article for … far too long now. I’ve put it off because, no matter how much I think I know about water with respect to brewing, I also know that I just don’t know enough. It’s a complex field, still not fully understood, and sometimes it feels like each question answered leads to five more to ask. Scared yet? Well, don’t be. It’s often said that one shouldn’t let the great be the enemy of the good, and so I’m going to go over the basics of water chemistry as it pertains to making your own beers better. If you want to know as much as a mere mortal can learn about the subject, I’ll always defer to John Palmer’s famous Water book. I’ve been fortunate enough to share some judging time and a beer with John, but alas, none of his immense knowledge transferred itself magically to me. I’ll just have to settle for the basics, and if there’s something in his book that contradicts what I write here… guess who is correct? Hint: not me. I will try to gloss over the technical chemistry as much as I can as this article is aimed at the non-technical brewer who just wants to understand how to get the best out of their water. With that said, there are some technicalities that must be explained (or at least roughly understood).
We will do a lot of talking about ions. An ion is a positively or negatively charged atom - ie. It has a net positive or net negative charge due to gain or loss of electrons. When mineral compounds are added to water, a polar solvent (google it!), they separate into ions. We will talk about mineral content as ions, and will use parts per million (ppm) and parts per billion (ppb) to represent one ion of the mineral to one million or one billion parts of water (H2O) respectively.
Why does water matter?
As per the title of this article, water is the main ingredient in beer by quantity! While “good tasting” water is very important, it’s not the be-all and end-all. In fact, it’s possible to have great tasting water that makes terrible beer. It’s common advice (and I’ve given it myself) that water adjustment should be the last thing you’ve paid attention to after mastering all the other parts of the process. Over the last decade or so, I’ve slowly come around to the opinion that this only works if your water is fairly good for brewing in general, and, in fact, it’s really important to get your water “in the ballpark” before anything else. Why? Because the composition of your water plays a part in every part of the brewing process from the mash, right through to the foam as you pour your beer into a glass. Let’s break it down.
First, let it be clean!
I have met people proud of the fact that they brew with RO water (reverse osmosis filtered water - pretty much pure H2O). That is indeed as clean as water can be, but the mineral content of water is very important to brewing. The various ions in the water not only change and enhance the flavours in the finished beer but play an important part in creating the right environment for fermentation during the mash. So, while we don’t want “pure” water, we DO want clean water - water free of contaminants such as environmental pollutants, or excess chlorine or chloramines added by water treatment plants to deal with pathogens. For this reason, it’s a good idea to buy a simple, cheap carbon water filter and run all your brewing water through that as a first step. This will retain the mineral component of the water while removing most of the things that we wouldn’t want in there such as chlorine.
Know what you have
Councils publish water reports of your local water supply. These are generally aggregate reports, consisting of the combination of multiple sources around the locality, and are sometimes not frequently published. If you have a local brewery, they are likely to have an updated water report for their particular water supply, and hopefully get it updated at least annually - enough for more accuracy. They will almost certainly be happy to give you a copy of this. Once you know what’s in your water, you can begin to tailor it for your needs.
The things we brewers care about on a water report are:
Total Alkalinity: Usually expressed as CaCO3 - Highly alkaline water makes mashing difficult and MUST be adjusted - ideally by dilution with RO water or similar. Desired range is 0-100 ppm.
Calcium: Helpful for healthy fermentation, wort clarity, and mash pH adjustment. Desired range is 50-150 ppm.
Chloride: Helps express malt flavour in the finished beer. Desired range is 0-100 ppm.
Magnesium: While magnesium is very desirable in the mash for clarity, yeast health, and mash pH, your malt will usually provide enough. Hence the desired range in water is 0-40ppm.
Sodium: Enhances flavour, but requires a delicate hand. Easily added, so the less in your base water, the better! Desired range is 0-50 ppm.
Sulphate: Promotes and enhances hop flavour and bitterness. Desired range is 0-250 ppm.
Bicarbonate: Sometimes not present on NZ water reports, but can be derived from the calculation 61 * Total Alkalinity / 50. Desired range is 0-250 ppm.
pH: A measure of the base acidity or alkalinity of our water. Desired range is 5-9.5.
Know what you want
When adjusting water, it’s good to know exactly what you are targeting. Think about the flavour profile of your desired beer, and decide whether you want hoppiness or maltiness emphasised. Do you wish to raise or suppress bitterness? Do you want a crisp, clean finish or would you like the flavours to linger? In short, think like a chef! Write down what you want, and then you can begin to think about how to modify your water to achieve that goal.
But first, the mash!
Mineral additions in the mash are very important, as they will a) build the environment for fermentation and wort clarity, and b) lay the foundation for the flavour profile that “chef you” created above. pH is the most important factor for fermentation health, as it promotes good enzymatic action and thus conversion of your starches to fermentable sugars. I’ve talked about this at length in a previous article. In order to target a specific mash pH, you need to know not just the pH of your water, and the effect of your malts and mineral additions, but you need to understand the concept of residual alkalinity, at least at a basic level. Technically, residual alkalinity is the resultant combination of the total minerality (hardness) of your brewing water and the alkalinity in the mash. You can think of it as “push back” by the mash on attempts to lower the pH in order to acidify it into the healthy mash pH range of around 5.2 to 5.6. The higher the carbonate content of the water, the higher the residual alkalinity, and the harder you will have to work to lower the pH with acid additions. I use lactic acid at 80% concentration for my mash pH adjustment, but any food grade acid is just fine. Citric acid is a popular addition. Residual flavour from various acid additions is often debated, but hasn’t proved significant as far as I am aware. If adding acid to the mash, ensure it is well blended. Ideally blend it in your strike water first.
What to add and how much?
You’ll need the following mineral compounds to adjust your water, in decreasing order of how often you’ll probably use them:Calcium Sulphate aka Gypsum - adds Calcium and Sulphate, lowers pH
Calcium Chloride - adds Calcium and Chloride, lowers pH
Magnesium Sulphate aka Epsom Salts - adds Magnesium and Sulphate, lowers pH (inefficiently)
Bicarbonate of Soda aka Baking Soda - adds Sodium, raises pH
Sodium Chloride aka Salt - adds Sodium and Chloride, raises pH
I’m avoiding Calcium Carbonate aka Chalk as it’s very hard to dissolve in water, but if you have an efficient method of dissolving it, then it adds Calcium and raises pH.
Because these are all compounds - ie. you can’t just add “sulphate” without getting calcium or magnesium too, you’ll need to be cognisant of ion limits, and for that, you’re going to want some software! While all the calculations for mineral additions are online and easily googleable (it’s a word now… I think) it’s best to use something tried, tested, and bug-reported! I like Martin Brungard’s Bru’n Water, although it requires Microsoft Excel for full functionality, it does work just fine under LibreOffice, and with some slight brokenness as a Google Sheet. Most brewing software also includes water chemistry calculators.
What you’re wanting to do is mainly to adjust the sulphate:chloride ratio, while keeping all other ions within their recommended ranges. A sulphate:chloride ratio of 1:1 will give a balanced, neutral flavour outcome, while still allowing the various minerals to enhance the hoppiness and maltiness of the beer. Note that you can achieve a 1:1 ratio but still be at the high end of the range for sulphate and chloride, and this may lead to extreme or messy flavours. Start subtle and iterate with future brews. The more you favour sulphates in the ratio, the higher will be the perception of hop flavour, but also hop bitterness, and it can be easy to get harsh, biting character if you go too far. Conversely, higher chloride:sulphate will give a richer, softer, and smoother malt profile. It’s harder to overdo the chlorides than the sulphates, though if the beer starts to exhibit a mineral character such as salty or alka-seltzer like, then you might have gone too far! Again, iterate and adjust with each brew.
Have a look at some classic water profiles and think about the types of beer associated with those when building your own water profiles. Be careful not to slavishly copy them though. A good example is the old Burton water profile for English IPAs. While historically, there may have been over 700 ppm of sulphates in the water, it’s very unlikely that level was present in the mash, as the resultant flavour in the beer would not have been pleasant! More information is needed. Or a TARDIS.
While you digest that lot, I’ll be back in part two to work through some real world examples.