When used in brewing, water isn’t about the romance of mountain springs or glacier-fed northern lakes. It’s all about chemistry, which lots of people consider to be a dry topic (if you’ll pardon the pun). However, as chemistry goes, this is pretty basic. Water is often defined as the universal solvent. This due to its component atoms, two hydrogen and one oxygen, these balance results in a balanced molecule, but with a positive and negative charge at each end. These charges are vital when dissolving different substances. When ionic compounds such as mineral salts enter a solution, they split up, and move to either end of the water molecule. These parts are known as ions, and also have a charge. When brewing it’s important to consider the amount of these ions which are present in the water you’re using.
These minerals are found in water naturally due to water interacting with rocks as it runs through the earth. In locations with limestone geology, the water acquires calcium carbonate and produces hard, alkaline water, which is very common. In locations with volcanic rock, the minerals present in the rocks are usually insoluble, so the water stays soft. There is a fairly unusual occurrence which takes place in areas where limestone has been altered by volcanic activity to form gypsum; this mineral produces an acidic hardness.
Minerals which have been dissolved in water may present some flavours of their own however, more importantly, they alter the chemistry and pH of the mash, and also change the flavour of hops in particular ways. Until around 1880, brewers didn’t really appreciate water chemistry, so they had to make do with the water which was around them. The majority of the world’s great beer styles began this way. Nowadays, we have the comfort of brewing any beer style wherever we want, now that we can treat the water to make any profile we want.
There are two extremes to treating water for brewing. You can jump in and re-create classic brewing waters down to the last ion, calculate every batch second-by-second with a pH meter, and pretty much be a massive water nerd. If this sounds fun to you, go for it. And if you’re a million-barrel-a-year brewery, this is probably necessary. But for us home brewers, this isn’t necessary, however you should consider it if you want to produce the best results.
The Big Six Water Minerals
There are only a few ions in most water sources which play major roles in mash chemistry, pH, and beer flavour. The positively charged ions, which includes calcium (the most important one), magnesium, and sodium and the negatively charged ions, which includes bicarbonate, sulfate, and chloride. All of these ions have different effects on mash chemistry and beer flavour. Calcium or magnesium bicarbonate provides a temporary hardness which is easily be eliminated by a number of techniques. Calcium or (less commonly) magnesium sulphate is a lot harder to eliminate and therefore is considered to be a permanent hardness.
Positively and negatively charged ions merge to create mineral molecules in certain amounts; this means there is a particular ratio of calcium to carbonate, for example, or sodium to chloride. This needs to be kept in mind when adding or removing minerals. When removing carbonate, we can eliminate only as much of it as there is calcium to couple with, which of course eliminates calcium. However, because calcium is vital for good mash functioning, we have to add it back in, however this also adds other minerals such as sulphate or chloride with it, and these have different effects of their own.
While these have little to no effect on mash chemistry, they are necessary for yeast nourishment —mainly copper, zinc, and magnesium. Though, in large amounts these can cause issues such as off-flavours and haze formation. All but the softest water has a generally decent mix of trace minerals, while some yeast experts feel that most fermentations can be enhanced by the supplement of small amounts of zinc, which is removed during the mash.
Heavy Metals and Other Contaminants
Brewing water needs to be of excellent drinking class, and cities need to meet EPA standards for metals, pesticides, nitrates (a marker for organic pollution), and others. Lead and iron ions be in water from pipes, usually if the water is particularly soft or acidic, the same is true of brewing equipment. Brass fixtures usually contain lead, as it makes them easier to drill and machine. Water from wells needs to be tested, particularly if it’s from mountain regions or areas where mining takes place, as dangerous chemicals, even arsenic can be present. These are chemicals are pretty hard to remove, so in those cases, just use distilled water instead.
This is added to most water supplies these days as an antimicrobial, either as free chlorine or a chemical known as chloramine. Whilst chlorine is not unsafe, free chlorine is extremely reactive and can join with phenolic compounds present malt and hops to create chlorophenols, a class of tenacious and foul-smelling chemicals which smell similar to bandages and electrical fires. Boiling or standing overnight removes free chlorine, but not chloramines. Carbon filters will eliminate both, but vary with chloramines, which also usually necessitate a slow flow through the filter for best outcomes. Potassium metabisulfite (Campden tablets) can also be utilised to eliminate either form of chlorine. One 0.5-gram tablet, crushed and dissolved, is able to dechlorinating (or dechloraminating) 20 gallons/76 L of water. This method is basically instant.
First thing’s first, you need to find out what sort of water you have. The water in different areas vary depending on the underlying rock formations from where the water is drawn, in some areas, the actual water source can be far from the tap. To make things even more complicated, there can be seasonal changes in the chlorination level (often higher in the summer) to frequent changes in water sources. Public water supplies are obligated by law to provide the public with an analysis, these documents are usually fairly easy to get hold of and allow you to make changes as necessary. Well water is more inconstant, and if you’re drinking it, you should definitely be testing it. If you’re in a hard water area, well water is usually twice as hard than the ground water, and can have contaminants such as sulphur and iron present.
In the majority of places, water will be somewhere on the spectrum in-between very soft and very hard and alkaline (temporary hardness) water. Sulphate water is pretty rare, so we’ll deal with it later. “Soft,” for brewing aims, is anything below 60 to 70 ppm of bicarbonate. Around these levels, alkaline minerals are not likely to have much effect on mash chemistry or hop flavour.
Next, we need to think about the style of beer we’re trying to brew and what we need to do to the water to achieve it. This is best done by focusing on tradition and forgetting the complex calculations which allow you to exactly target your mash chemistry and pH levels. How accurately you need to play around is a matter of personal preference. It is absolutely possible to brew great beer by just observing some general principles, and as a matter of fact, the majority of the great craft breweries in the United States do very little in the way of water treatment unless they have extreme water.
You certainly need to eliminate the chlorine added to public water supplies. Free chlorine is removed by all carbon drinking-water filters, however, for best results; limit the flow to around 1/2 gallon/2 L per minute. Nowadays lots of public water supplies use chloramine (NH2 Cl), this is more challenging to remove. Very high-quality carbon filters will do the job, but a slow flow rate is suggested. Otherwise, Campden tablets (potassium metabisulfite), usually found in the winemaking section of your homebrew shop, do a good job, by simply dissolving one-fourth of a 0.5-gram tablet per 5 gallons/19 L of brewing water, then letting it stand for a couple of minutes.
You need to keep two things in mind about your beer recipe: the colour and the bitterness level. Colour alters the mash pH as coloured malts are far more acidic than the paler ones. As a result they can offset the effects of alkaline water, and the famous centres of dark beer production (Munich, London, Dublin) all have notoriously hard, alkaline water. Bitterness is vital, as pH has a great effect on the way hop-bittering compounds are incorporated into beer. At high pH (more alkaline), hop bitterness develops into an astringent, harsh taste.
Basically, dark beers and paler beers which lack a great deal of bitterness can withstand some alkalinity in the brewing water. Munich water, has just less than 170 ppm of bicarbonate, it is particularly famous for brewing dark beer, however they also produce a fantastic pale lager known as helles with their hard water, but the BU is around 20 or so, low enough not to fight the alkalinity. That amount of carbonate (200) is pretty much the limit; if your water is above that, you’ll definitely need to treat it.
If your water is below the 200 ppm carbonate range, you’re in a great position to brew dark, non-hoppy beers. This chart sums it all up. However, if you want to brew pale and hoppy beers, you’ll need to alter the water. The most obvious thing is to add some acidity in order to counteract the alkaline carbonate, and this is occasionally done, either with sour malt or food-grade lactic or phosphoric acid. But, carbonate is a great buffer which can soak up a lot of acidity while remaining in the solution to cause problems, and at a certain level too much acidity can be tasted.
A better solution is to remove the carbonate completely. The common method used by homebrewers is to boil the water, removing the dissolved CO2 gas, converting soluble bicarbonate into insoluble carbonate which then sinks to the bottom of the vessel. This is the well-known lime crust which forms at the bottom of kettles. When it precipitates, the carbonate acquires a precise quantity of calcium with it. In effect, the quantity of calcium is a limiting factor, as carbonate can precipitate only to the extent that there is calcium in the water for it to combine with. So most home brewers add calcium sulfate or calcium chloride to replace the calcium removed.
This chart displays the colour and bitterness, the two key features which determine the type of minerals required for good brewing water chemistry. At the bottom left are pale, hoppy beers, which need to be brewed from water with carbonate content lower than around 70 ppm. At the top and right are dark and non-hoppy beers which can be brewed from water with up to 220 ppm of carbonate. All beers, irrespective of colour, require at least 50 ppm of calcium for good mash chemistry.
Usually, some gypsum or calcium chloride is inserted into the water prior to boiling in order to remove carbonate. After a quick boil, the water should be drawn off, departing from the calcium carbonate left behind. How much you need to add depends on your water’s mineral content, around 2.5 grams of calcium sulphate (gypsum) or 5 grams of calcium chloride per 5 gallons/19 L usually does the job for most water in the 100 to 200 ppm of carbonate range, and will leave you with enough calcium for good mash performance.
A simpler option is to dilute your carbonate tap water with distilled or RO water to reduce the carbonate content down to 70 or lower. Lots of breweries decarbonate using slaked lime (calcium oxide), this eliminates CO2 without the need to heat the water, however, this needs precise calculations to get it spot on.
Common Water Issues
Water which has a lot of calcium sulphate is present is called “permanently hard,”. There is no simple way to remove it. Sulphate isn’t as undesirable for brewing as carbonate, but it does have a certain character which can be out of place in any beer which isn’t a hoppy, not-too-dark beer.
Those of you which have very soft water, the opposite problem is true as well as a new one. Whatever you brew requires calcium in the 50 ppm range or higher. For pale lagers, the softer taste of calcium chloride works well. For the sharpness of a Burton-style IPA, you’ll need to add 5 to 120 grams per 5 gallons/19 L of calcium sulphate in order to attain the 150 to 250 ppm range of sulphate. It’s not a particularly soluble mineral, meaning you’ll need to stir it well and give it time to dissolve. There are some brewers who add large amounts of calcium and magnesium sulphates to emulate the super-minerally Burton well water, although I don’t think it’s needed.
If you’re brewing darker beers, calcium chloride does the job, but if you want to emulate more alkaline water, calcium carbonate, while not very soluble in water, will dissolve in the mash with the acidity contributed by dark malts; 120 to 150 ppm is usually a good range to aim for.
Soft water is lacking in trace minerals. For healthy yeast, zinc and copper are vital, in addition to small amounts of potassium, magnesium, and others. Surprisingly, copper can be added by putting pennies or other pieces of the metal into the kettle, but for a stable brew, it’s best to use either a zinc-enhanced yeast nutrient such as Servomyces or to add a helping of bottled mineral water with a high mineral content.
The above is a generalisation, but overall, such an approach will yield great beer, as evidenced by most of the craft beer on the shelves out there. It is feasible to do much more detailed manipulations, including estimating and compensating for residual alkalinity, which will allow you to predict your mash pH. These sorts of calculations are fun for some people, but headaches for others, so you have to decide how much precision you really want. The calculations you need can be found elsewhere on the internet or in books. Many of the brewing calculation software packages deal with water chemistry as well.