Adjusting Your Brewing Water
Beer is more water than anything else, which means that water is one of the most important ingredients in a brew. And, of course, water is a catch-all term for a solution of a variety of salts depending upon its source. So we should pay good attention to our brewing water, and as the professionals do we should adjust its contents to suit the beer we are brewing. But when, why, and how should we do that? There are two areas where water influences a beer — improving certain stages in the brewing process, and affecting the flavor of the final beer. If your approach is, “If I can drink it I can use it to make good beer” I’ll try to explain why you might want to change it, and try to keep my explanation as simple as possible.
Water in brewing
You are probably aware that the great traditional brewing cities such as Pilsen, Munich, London, and Burton on Trent all had different types of water and the beer styles that made them famous were all brewed to suit the quality of the available water. Your water will almost certainly not match any of these, whether it comes from a tap, a well, or a bottle. And if you think distilled water, as the purest form of the liquid, would be good for brewing, don’t, because you will be throwing away the resulting beer and I won’t come around to help you do so!
The main reason these different waters favored different beer styles is the effect that they had on the mashing process for different types of malt. Broadly, waters with high sulfate content were good for pale beers, while those with high carbonate content were more suited to brewing dark beers. That is because the pH (acid concentration) of the mash is of great importance in the enzyme driven conversion of malt starches into sugars.
Why so? Because the results of starch conversion vary according to whether mash conditions favor either one of the most important enzymes: Alpha- and beta-amylase. We control this in two ways, firstly through mash temperature, generally keeping it in the range 148-154 °F (64-68 °C). Beta-amylase is favored at the lower end of this range and alpha-amylase at the higher end, and the lower the temperature is the more fermentable the wort will be, while higher temperatures favor production of a more dextrinous wort. In short, the temperature you decide on is a compromise, depending upon what you want to achieve.
Mash pH is also a compromise since the two enzymes are at their most efficient at slightly different pH levels. Beta-amylase “likes” pH 5.4-5.6 and alpha-amylase 5.6-5.8. The choice of many brewers is a pH of 5.2-5.5, the low end of the range having been selected so as to promote the action of other enzymes such as limit dextrinase, a starch-debranching enzyme. Mash pH is controlled by a combination of malt acidity and the salt content of the brewing water. The chemistry is fairly complicated, but basically calcium salts in the water liberate acidic phosphates from the malt that brings mash pH down from that of the water (most drinking waters are around pH 7).
But there are two important salts to consider, calcium sulfate and calcium carbonate (the latter actually being present in the water as calcium and bicarbonate ions). Calcium sulfate tends to bring down mash pH, but bicarbonate is what is known as a buffer, which means in effect that it resists change in pH. And the buffer effect of the bicarbonate is stronger than that of the sulfate, so that it is difficult to reach the desired mash pH when using water high in bicarbonate. The latter is particularly true when mashing with only pale malt, but if significant proportions of high roasted malt are being used the acidity of these will in fact bring the mash pH to where the brewer wants it to be. That is why high bicarbonate waters, such as those from London, were so suited to brewing porters and stouts, and those high in calcium and sulfate were ideal for brewing highly-hopped pale beers, such as the IPAs from Burton on Trent.
But how do you know what sort of mineral content your water has? Well the obvious solution (not a pun) is to have it analyzed. Easy enough if you have a town supply, just ask the utility for an analysis, and the same if you are using bottled water. If you have well water you can get it analyzed reasonably inexpensively at a suitable local laboratory (I have a water testing kit specifically designed for homebrewers from LaMotte, which you might alternatively want to look into purchasing).But if you are not a chemist you may find it difficult to interpret any such analysis since it will mostly give only the contents of individual ions. What you need to look for is hardness and alkalinity, both usually measured as CaCO3. If the hardness figure is higher than that for the alkalinity then the hardness is largely “permanent,” that is it is largely due to the presence of calcium sulfate. If the alkalinity value is the higher of the two then the hardness is “temporary,” which means it is largely due to the presence of bicarbonate ions.
If the alkalinity is higher than about 50 ppm as CaCO3 and you want to mash with only pale malt, then you have to reduce this figure. It is called temporary hardness because boiling the water will convert bicarbonates to insoluble calcium carbonate. So the easiest way to reduce bicarbonate is to boil all the water you use, allow the solids to settle, and then rack the water from the sediment. This has the added benefit, if you are using a chlorinated water, of removing much of the chlorine. Depending upon the level of permanent hardness and the type of beer you are brewing you may need to add some calcium sulfate (as gypsum) after removing the bicarbonate. And note that boiling does not remove chloramine, which sometimes is used to treat water. Ask your utility if that is the case, and if so, you would be well advised to use an activated carbon filter. These are not expensive and come in a cartridge form that fits in the supply line just before the faucet. Do not be tempted to use ion exchange resin systems; they will mainly exchange calcium for sodium. And high levels of sodium can make the beer taste harsh and may have a deleterious effect on the yeast you use. One final point is that brewers do not worry too much about the pH of brewing water. That’s because it bears no relation to the mash pH achieved, which is determined by the malt acidity and the buffering effect of salts such as bicarbonate. Of course that doesn’t apply to acidic (say below pH 6) or alkaline (say pH 7.5 or higher) waters, which should not be used for brewing anyway.
I recommend you test the pH of your mash even if you think the water is suitable for the style of beer to be brewed. Homebrewing suppliers usually offer pH test papers for this, which just need to be wetted with a little of the mash to give a reading. However, these are only accurate to 0.5 pH units, which means that they will not really help if you are aiming at pH 5.2-5.5, since if the papers read 5.5, it may actually be anywhere between 5.0 and 6.0. Better to bite the bullet and buy a pH meter; handheld meters are available and run from about $60 upwards. These are accurate to +/- 0.1 pH units, but must be calibrated against standard buffer solutions (which will also be available from your supplier) at every use. You will also need some storage solutions in which to keep the instrument when not in use; these ensure that the electrode does not dry out between uses. Do buy a meter of decent quality, as the cheapest meters do not last as long before the electrode has to be replaced.
So, take your meter and measure the pH of the mash right after you have mixed the water and malt. If it falls in the range 5.2-5.5 you are fine; if it is above this range then add some gypsum (5 g, or a teaspoon), stir it in and re-measure. If it is still above 5.5 add more gypsum; if that doesn’t work you have a problem with bicarbonate and should have used the boiling treatment recommended earlier. So long as it is below pH 6 you can still go ahead and brew the beer, but both yield and flavor may be somewhat disappointing, and you should remove bicarbonate before the next brew. Conversely, if you are using a lot of high-roasted malt (black, chocolate, and so on) and get a reading below 5.2 you may actually need to add some bicarbonate ions to the mash. Just take some precipitated chalk (about 5 g) and stir well into the mash, then re-measure pH with your meter. Repeat if necessary. Note that you cannot add chalk to the water before mashing as it is not very soluble in water; if you want to do it that way add sodium carbonate instead.
So far I have dealt with the effects of water quality in mashing, which is not so important in extract brewing where the mashing has already been done for you. But calcium ions are also important in other ways for they help to form a good hot break during boiling, and also help yeast flocculation. There are flavor effects too as we’ll see later.
Detailed water adjustments for particular styles of beer are beyond the scope of this article, which I have tried to keep simple. If you want to look further into this I recommend the brewing water spreadsheet that can be found on the BYO website at www.byo.com/resources/brewwater. This comes from Greg Noonan, one of the fathers of craft brewing and a water treatment maven if ever there was one!
Water for flavor
The mineral constituents of water can have a significant effect on beer flavor. I have already discussed calcium and bicarbonate, but perhaps the next most important ion is sulfate, which can give the beer a dry, sharp finish. It has an important impact on highly-hopped, bitter beers since it makes for a very clean and more pleasant bitterness. Sulfate is obviously important in pale ales and especially IPAs. In such beers it can have a concentration of as high as 350 ppm, which amounts to approximately 13 g gypsum in 5 gallons (19 L). Personally, I usually add to the mash 5 g gypsum to 5 gallons (19 L) for such beers, which works out to around 130 ppm sulfate, for my water is quite low (less than 50 ppm) in total dissolved solids. Such additions may not be necessary for extract brews depending upon the manufacturer’s process, but if your extract IPA is giving you a somewhat harsh bitterness it is probably worth adding a little gypsum to the boil next time.
Magnesium ions are often present in high-sulfate waters and can help to accentuate beer flavor but should be present in relatively low concentrations, say not more than 30 ppm. Above that it can impart astringency, and at higher levels it can have more unpleasant effects. Epsom salts, magnesium sulfate heptahydrate (MgSO4.7H2O), has long been known as an efficient laxative! If you have high levels of magnesium in your water it would be prudent to look for another source.
Chloride ions also have a significant effect on beer flavor, and can increase the perception of bitterness. But these ions also add a fullness to the beer, making it mellow and satisfying on the palate. Accordingly, their presence is important in beers having low hop bitterness levels, notably mild and brown ales, as well as brown porters. I have heard of chloride levels as high as 250 ppm in British mild ales, but I think that is somewhat excessive as such concentrations can give the beer something of a “salty” taste that I find unpleasant. However, with my very soft water I do add to the mash 5 g table salt (NaCl) for a 5 gallon (19 L) brew, which comes out to around 150 ppm chloride. If your water analysis indicates a level of around 100 ppm chloride, further addition is probably not necessary. Again, extract brewers might want to consider adding salt to improve dark, low-hopped beers.
Sodium ions have a definite effect on flavor, making for a crisp clean finish in the beer. Several pre-Prohibition lagers I have come across add salt to quite soft waters for this very reason. Since salt provides both sodium and chloride ions you can get this effect using the salt addition suggested in the previous paragraph.
Water treatment is a very complicated subject and I have really only touched the subject here. I recommend again that you look at the BYO spreadsheet for any particular beer, and adjust accordingly, but do always check mash pH.
