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Shifting Water: Understanding brewing water additions

When John Palmer and I were writing Water: A Comprehensive Guide for Brewers, many brewers had not taken the time to understand the basic chemistry that establishes mash pH. Now, a decade later the concepts presented in the book have become a normal part of the new brewer’s education. Recipes are now sometimes written with the water profile included and water calculators are everywhere online.

It is important that a brewer chooses a water strategy that matches their water source. It would be absurd for a brewer in Pilsen to purchase a reverse osmosis (RO) system for their water as their water is already very soft. It would also be absurd for a brewer in Dublin to try to make a Pilsner by simply adding acid to their water to reduce the alkalinity. So that begs the question . . . how do we make a strategy of our own?

The first thing I would highly suggest is to understand the source of your water. When I was a Head Brewer in Napa, California, I got my water from three sources and they were very different from each other. My water usually came from Lake Hennessy Reservoir that had about 100 ppm alkalinity, 5 ppm Ca2+ and 20 ppm Mg2+. This would vary significantly seasonally. When there was a lot of rain this profile would be diluted and if there had been a long dry spell it would be concentrated. My water recipes had to adapt. In the beginning I would measure five key ions every brew: Calcium, magnesium, chloride, sulfate, and alkalinity. After a few years I realized that for the English ales I was making, I was always going to add calcium, no matter if the level was 3 ppm or 10 ppm, the baseline calcium level did not play a significant role in this addition. However, the difference between 50 ppm and 120 ppm of alkalinity was a significant factor in my mash pH. For this reservoir, measuring the alkalinity was sufficient for me to understand where the water chemistry was at that time and allow me to adjust my additions. This was a concept that took me years to fully embrace.

In the winter that reservoir often proved problematic for the water department. Sometimes there was not enough water, or at times there would be an algae bloom that required significant additions of copper to the reservoir, or the water required significant additions of chlorine. During those times of duress, they would switch to a different water supply, the North Bay Viaduct. Their first choice was to bring water in from the Sacramento Delta. This water inlet was in a slough and the water did not move through it very quickly. Above the inlet was a large depression where cattle grazed. During large rainstorms the depression would become a pond and overflow into the inlet. This would spike the coliform count from the cattle and cause the water department to dramatically increase the chlorine levels in my water. The combination of all the organic material and chlorine made for some strong off flavors, not only in the water, but in the finished beer as well.

This water was the hardest for me to work with as the chlorinated organics had flavor thresholds in the ppb range. My strategy for this water was slow passes through fresh carbon filters. Once the water was filtered and collected I would taste the water for a final approval. There were quite a few occasions where I drained the hot liquor tank and started again. There were two occasions in 15 years where I was not able to brew for at least a week. Both times the tap water tasted so bad that Napa residents complained and the water department would switch to their last option, which was also my preferred water source.

The first thing I would highly suggest is to understand the source of your water.

This last choice water for the local water department was a nearly perfect water source, the Milliken Reservoir. Very low in minerals and very low in organics. It was their most expensive choice so we only got it a few weeks a year. When they would switch I would borrow a lager yeast from another brewery and make a Pilsner style beer as it was the only way I could get suitable water without an RO unit, something that was out of my budget.

As you can see, my water was never consistent and as the brewer I was required to adapt to my incoming water. This is not at all uncommon. Learning about the sources of your water and how they change seasonally is an important step to gaining control over your water chemistry and making a recipe consistently.

Even if we had a perfectly consistent water source, different beers require different water profiles. It is not hard to make a new water recipe but it does take some time and experimentation. If we are producing a classic style then it will help us to look at the traditional water from the region. This is not the last word in the water as many brewers are changing the water to fit their style, not the traditional style. I didn’t realize this in the beginning and one day I was adding a bunch of gypsum to a kettle when a customer walked by and asked what I was doing. I explained that I was making my IPA and that IPAs came from Burton upon Trent and they had a lot of sulfate in their water. He smiled and said, “I am a brewer in Burton upon Trent and we hate our water.” That got me thinking and I started researching how different regions pretreated their water for their local styles. I found that many classic regions also had traditional as well as modern water treatment methods in place.

Also, I was producing very California-esque renditions of English styles and was not married to hitting the British waters. I needed a way to develop water recipes that worked for our brands. I was unable to find anything written about this so I started from scratch. First, I knew I wanted to hit my target mash pH. The literature taught me that mash pH effected the efficiency of the mash. If I maximized the efficiency I would save some money on malt. I looked into the numbers and realized that since I was only producing 750 BBLs per year the money was not worth chasing.

If you change your grist-to-water ratio, you are changing the weight of the ions added and the dilution rate of the ions derived from the mash.

In talking with brewers I was hearing that the boil pH was changing the hop characteristics. One famous brewer taught me that raising the boil pH allowed them to lower the amount of hops they used in the bittering addition. This also was not a financial motive for me but it opened the door to understanding how the pH affected the bitter quality of the beer. I couldn’t stop beer production while I learned all of these things so I had lots of batches and good notes to consider while coming up with a strategy.

Of course I had a few mistakes along the way that also gave me good data points. One thing that was clear was when the boil pH got too high (we can use 5.6 as the extreme) the bitterness became harsh. When the boil pH got too low (we can use 5.0 as the other extreme) the beer was “lifeless.” I produced beers of all colors and all hop levels so it took some time to sort out a strategy. I finally ended up liking light hoppy beers at a boil pH (measured in a 68 °F/20 °C sample) of 5.4. If I did my homework that morning on the water in the hot liquor tank, no adjustments would be needed at the beginning of the boil, just the hot liquor tank. If I consistently had my West Coast-style IPA at 5.4, as an example, I could adjust the hopping to get the flavors I was happy with. Does that mean it’s the only strategy for making an IPA? Absolutely not. If I wanted different bitterness qualities I could have added a larger 60-minute addition at a pH of 5.2 and kept the same perceived bitterness with a different quality.

This is a good place to mention that when and how you measure your kettle pH must be consistent. I picked the moment the kettle was full and before boil and then chilled my sample. This kettle temperature (180 °F/82 °C) and time was always the same because of the process control I had in place. The reason this is necessary is the calcium and magnesium will continue to bind with phosphates in the boil and settle, effectively lowering the kettle pH. The degree of this change depends on the minerals available at this stage of the brewing and the limiting factor is usually calcium. Some brewers will add minerals at this point to provide more calcium. This has the effect of lowering the kettle pH during boil and provides more calcium for the fermentation. It also very likely lowers the oxalate level in the fermenter but beerstone control is beyond the scope of this discussion.

Once I had a target pH, hitting it was simply a matter of doing the traditional residual alkalinity (Ra) math:

Ra = (alkalinity in ppm x 61) – (Ca in ppm x 20 / 3.5) – (Mg in ppm x 12.1 / 7)

And keeping that value constant with my varying water supply, assuming my grist-to-water ratio remained unchanged. If you change your grist-to-water ratio you are changing the weight of the ions added and the dilution rate of the ions derived from the mash. Remember, adding more calcium or magnesium will lower mash pH and adding more alkalinity will raise mash pH.

Brewers who have started to focus on their water know that a reverse osmosis (RO) system can be a game changer when it comes to water treatments. Photo courtesy of StickerGiant

The other thing that was clear from these experiments was that chloride and sulfate were making it into the finished beer and had a significant flavor component. To a limited extent they counteracted each other. So, if I needed more or less calcium and magnesium to hit my mash pH with the water collected that day I could adjust my salt additions as long as I kept the sulfate-to-chloride ratio the same. Some people have tried to take this to the extreme, and try to infer that 500 ppm sulfate to 50 ppm chloride is going to taste the same as 50 ppm sulfate to 5 ppm chloride. This is not at all what I mean. What I am saying is if you need 20% more calcium to hit your pH then you are best getting it from a blend of salts that matches the sulfate-to-chloride ratio if you want the flavor to stay consistent. This ratio is a useful tool . . . with limits.

This begs the question of what sulfate-to-chloride ratio do we want in a beer? Of course the answer is, it depends on what your goal for the beer. This is a great way for a brewer to show his mastery of their ingredients. When I am formulating a new recipe, I brew it to my best guess, making sure the pHs hit my targets along the way and then I make up some spiking solutions. I take a teaspoon of gypsum and mix it into a pint of water and I take a teaspoon of calcium chloride and mix it into a pint. (You will quickly notice how hard it is to dissolve the gypsum by comparison.) By adding a drop of one of the solutions you will find which direction you would like to shift the recipe. At some point you end up with a salty mess and have to start with a fresh pint. It would be easy to do the math of how much sulfate and chloride we are adding but this does not help us formulate the next recipe as the brewing process will cloud the exact contributions. It does, however, give is an idea for where to shift the recipe.

I found that adding gypsum made the beers crisp and bright. Adding calcium chloride made the beers full and round. Interestingly, a significant amount of magnesium also survives into the glass and I found it also had a strong flavor component. For me adding magnesium gave dark malts a fuller, more complex flavor. Using Epsom salt as a spike can also be enlightening, especially in Kölsch and dark beers.

Many brewers save understanding water for last. I strongly suggest you do not delay in learning this important ingredient in beer.