Water Adjustment


Step 5: Brew Day

During our brew day we add the various salts measured in the previous steps to the mash and to the boil, and make other water adjustments. For sake of completeness, below is a summary of the water adjustment steps we follow, some taken from our Brew Day: Step by Step guide and Parts List for Using Your Brewery.


Removing chlorine/chloramine

Chlorine (or chloramine) is added to most public water supplies to kill disease-causing bacteria that the water or its transport pipes might contain. If left in, both can give beer a Band-Aid or plastic taste so it's best we get rid of it. We do this by adding potassium metabisulphite to our water at the start of our brew day.

Typical municipalities use up to 3 ppm of chlorine or chloramine in their water. Treat this water at a rate of 500mg of potassium metabisulphite per 20 gallons. We always start with 20 gallons of strike/sparge water in our Hot Liquor Tank and our municipality uses ~2 ppm of chloramine so a single 500mg dose is perfect for us. There's no harm in adding potassium metabisulphite if you're unsure if your city uses chlorine/chloramine.

We prefer the powder form of potassium metabisulphite and use a jewelry scale with 0.01 gram resolution to measure out 500mg. Campden tablets which are approximately 500mg are also available which can be either sodium or potassium metabisulphite. If possible, we recommend limiting the use of sodium in beer so use the potassium metabisulphite version if you go with tablet form (though the amount of sodium is arguably so miniscule to not make any difference).

We add this potassium metabisulphite directly to the Hot Liquor Tank after filling it with water at the start of the brew day. The chemical reaction is instantaneous, no waiting required.

Potassium metabisulphite loses efficacy over time so do not stock up. Most manufacturers recommend keeping containers tightly sealed and storing in cool dry conditions at room temperature. Shelf life is typically 12 months from the date of manufacturing.

Some brewers choose to use activated carbon based water filters to remove chlorine. Carbon based filters remove less chlorine as they become saturated, and the amount removed is directly related to the speed at which the water is passed through the filter making it difficult to know if the chlorine has been removed. This is why we use potassium metabisulphite instead. It's quick, dirt cheap, and works almost instantaneously. Activated carbon filters are also not overly effective at removing chloramine from water, requiring a more advanced reverse osmosis filtration system.

Note: Brewers from years ago used to be able to simply leave water out overnight in their kettles to allow chlorine to evaporate, but today many municipalities have switched to using chloramine as it is more stable (doesn't break down or evaporate as easily). Leaving it out overnight will do next to nothing.

Measuring out  potassium metabisulphite using a jewelry scale with 0.01 gram resolution:

500mg (half a gram) of potassium metabisulphite really doesn't amount to much:


Adding mash salts & acids

When it's time to add the milled grain to the heated water in the Mash/Lauter Tun, add the mash salts at the same time and mix well with the mash paddle.

Gently mixing the grain and salts with the mash paddle:

Remember that the mash salts we've added are primarily for flavour. Once well mixed and left for at least 10 minutes, we also need to confirm the mash pH. Most city water has a pH of 7.0 or higher but the pH range we want for our mash for optimal starch to sugar conversion is considerably lower. Fortunately the grains we mix with the water in the Mash/Lauter Tun are acidic (the darker the grain the more acidic it is) as are some of the mash salts we add. This helps to drive the pH down towards the proper range. We'll now check and add some extra acid if the pH isn't low enough.

Once the grains and mash salts are well mixed, take a pH reading by placing the probe tip of the pH meter directly in the mash. The pH meter we recommend has automatic temperature compensation (ATC) up to 140F so we do not worry about cooling down a sample as any errors introduced will be minimal as we usually measure the mash pH when the temperature is just slightly above 140F. While the probe electrode will last longer if the sample is first cooled to room temperature, ours (so far) has last 10 years when brewing once or twice a month, so we've never bothered cooling down a sample as it's much quicker. Feel free to cool a sample to room temperature if you prefer.

For optimal starch to sugar conversion we want the pH to be around 5.2 to 5.4, but only when measured in the mash temperature range of somewhere around 145-165F. pH changes with temperature, so if the sample has been cooled to room temperature, a pH of 5.4 to 5.6 is the target range instead of 5.2 to 5.4. Don't confuse the inclusion of automatic temperature compensation (ATC) in the pH meter to mean that the target range will always be 5.2 to 5.4 regardless of temperature, as that would be incorrect. ATC only compensates for the change in the electrical response of the pH meter probe with temperature. It does not compensate for the chemical/energy change in the water that naturally makes a hotter mash more acidic (lower pH). The pH target range will therefore always depend on the temperature of the sample: 5.2 to 5.4 when measured at mash temperature, or 5.4 to 5.6 when measured at room temperature.

Regardless of range, there is no 'one' correct mash pH as the various enzymes work best at different pH levels when converting the grain starches to sugars. While a wide range (from 4.5 to 5.6) is acceptable for mashing, most brewers will try and stay somewhere in the 5.2 to 5.4 range (when measured at mash temperature). A higher pH (more basic) produces a sweeter beer due to a less fermentable wort and more body. A lower pH (more acidic) produces a drier beer with thinner body due to a more fermentable wort. It also produces better extraction efficiency, better hot break formation, lighter colour, and is less prone to form haze.

The most common problem brewers face with a light coloured beer such as our Blonde Ale is that the mash pH will be too high. If your pH is above the 5.2 to 5.4 range (when measured at mash temperature), add some 88% lactic acid half a milliliter (mL) at a time using a 1mL (1 cc) syringe, stir well and wait for at least 5-10 minutes, and re-measure until you get close to 5.2 (when measured at mash temperature). It usually only takes one or two milliliters at most for most beers if you were able to hit the proper mineral flavour profile in the previous steps.

Mash pH at 5.21 after adding mash salts and a bit of 88% lactic acid. Perfect!

Some people chose to use 10% phosphoric acid instead of 88% lactic acid as they say it cannot be tasted as easily as lactic acid. This is not an issue as lactic acid in the quantities we use (0.1-0.2 mL per gallon) simply cannot be tasted even in the lightest of beers. You need at least 10 times the amount before it becomes noticeable. Some also say that phosphoric acid will precipitate calcium out solution which could throw brewing salt additions out of whack but they are only very miniscule/irrelevant amounts that will not affect the final beer. We choose to use 88% lactic acid as it works well for us. Feel free however to use whatever acid you like. Some other acids commonly used in brewing also include sulphuric and citric acid.

If you prefer to brew to Reinheitsgebot (German Beer Purity Law) standards where acids cannot be used, you may replace a small amount of the base malt with acidulated malt which contains a small proportion (usually 1-2% by weight) of lactic acid. How much is done mostly through trial and error as you brew repeat batches, as adding more will throw off your starting gravity since adding grain adds sugar. We find it simpler to add acid separately.


Acidifying sparge water

Before we sparge (rinse the sugars from the grain using the sparge water in the Hot Liquor Tank) we want to ensure that the pH of the water isn't too high. Too high of a pH can extract excess tannins from the grain husks. While all beer will have some tannins, with most beers (including this one) we want to try and minimize the amount. Tannins have a tongue-drying astringent taste like over steeped tea or strong red wine.

We want the sparge water pH to be below 6.0 (when measured at mash temperature), preferably in the 5.6 to 5.8 range. Before sparging take a pH reading by placing the probe tip of the pH meter in the Hot Liquor Tank . If the water is well above 140F you may want to extract a sample and wait for it to cool slightly first. (The pH meter we recommend automatically compensates for temperature but only up to 140F). To lower the pH, add some 88% lactic acid half a milliliter (mL) at a time using a 1mL (1 cc) syringe, wait a minute for the acid to recirculate and mix through the pump, and re-measure. It usually only takes us one or two milliliters at most in 10-13 gallons of sparge water to get down into the 5.6 to 5.8 range. All water is different however. Once you know how your water reacts, you'll be able to adjust it without having to measure the pH every time.

We usually acidify the sparge water while the mash is proceeding.


Adding boil salts & acids

After the wort has come to a boil in Boil Kettle and the foam (called 'hot break') has subsided, add the sparge salts to the boil.

If desired, after allowing a few minutes for the salts to dissolve and mix in the boil, take a sample and allow it to cool to around 140F and measure the wort pH using the pH meter. It should be around 5.0 to 5.5 (measured at mash temperature). If it is too high you may want to consider adding some 88% lactic acid to get it down into this range. If the mash pH was ok then the wort pH is most likely fine too unless the water you use is very hard. A proper pH helps produce a good protein break during the boil which in turn helps with beer clarity and long term stability. A boil pH that is too high can also cause harsh hop bitterness.

Measuring the wort pH in the Boil Kettle before boiling:

That's it! We hope you've found this water adjustment guide easy to use and that it helps you step your brewing up a notch.

See our Brew Day: Step by Step guide for further details on how these water adjustments are incorporated in our typical brew day.