This blog provides information for educational purposes only. Read our complete summary for more info.

Kyle Brown

Owner of Clawhammer Supply

Commercial breweries serious about making world class beer take great care to seek out quality water sources when locating their facilities. They generally look for naturally clean, relatively neutral, great tasting water, as well as municipalities that care for their water sources. And, of course, they filter and adjust the chemistry of their water to make improvements, as needed. Similarly, removing impurities, tweaking pH, and adjusting mineral content can have a positive impact on the final quality of homebrewed beer – which is particularly true of all-grain batches (as opposed to extract kits).

Why Adjust Brewing Water Chemistry?

As mentioned above, commercial breweries filter and adjust water chemistry, and for some obvious reasons many homebrewers choose to filter and adjust the water chemistry of their brewing water in order to make better tasting beer. But what are the reasons one might want to filter and adjust chemistry? Well, for one, better tasting brewing water will generally make better tasting beer. For example, if tap water tastes and smells like chlorine, it’s likely to make beer that tastes and smells slightly medicinal, or like band-aids! Another reason is that certain beer styles benefit from certain mineral profiles.

Before reading any further, let us say this: you can make some pretty solid beer without attending to water chemistry. Does your tap water taste good? If so, it’ll probably make decent beer. Could it be better? Maybe. But don’t sweat water chemistry until you’ve had a chance to make a few batches of beer and determine how good it tastes without chemistry adjustment. Once you have nothing better to worry about, dive into chemistry.

Step 1: Get a Water Quality Report

The first step in improving your brewing water is to establish some baseline chemistry by digging up information about your supply. Is your water hard? Soft? Alkaline? Acidic? If you live in a city, the easiest way to answer these questions is to find a pre-written report on the water.

Get online and look up your municipal water authority. You should be able to find a report that lists mineral content as well as pH. If this information isn’t published, you can always call your local MSD office and request a report, which they should be happy to provide.

Once you have a report in hand, skip down to the “Essential Minerals” section below.

No Report Available?

If there isn’t a report available or if you get your water from a well, water chemistry information likely won’t be readily available. You’ll need to collect a sample and use a home test kit or send the water to a lab for testing. If it’s well water that you’re testing, be aware, you’ll likely want to have it tested several times throughout the year because seasonal rains and snow runoff have a substantial impact on mineral levels.

Step 2: Compare Your Report to This Chart

Here is a breakdown of the desired ranges you’re looking for of elements in your water:

Source: The Big Book of Homebrewing

Step 3: Adjust Chemistry

Once you’ve determined the mineral content of your water and have compared it to the chart above, you’ll be ready to make any necessary adjustments. We’ve listed several important “flavor ions” below, as well as example additions (to reverse osmosis water) and the resulting impact on water chemistry.

Note, it isn’t easy to hit exact targets, so don’t fret if you can’t. Also, pH is probably a more important target to hit than actual mineral content, so focus on that first, especially when brewing light lagers and dark beers such as stouts.

Calcium

The first compound we’ll look at is is calcium. Higher calcium correlates with harder water. It actually plays an  important part of the fermentation process, as it is one of the nutrients yeast feed on, so this will be an imporant mineral to adjust if sufficient levels aren’t found in your brew water. Adding 2.5 tsp. (10 grams) of gypsum to 7 gallons of water will increase Calcium by about 90ppm. Note, it will also increase sulfate by about 200ppm, which is not a bad thing if you water needs additional sulfate.

Magnesium

Another important yeast nutrient is magnesium. If your brewing water needs more magnesium, you can increase it by adding Epsom Salt. Adding roughly 0.75 tsp (3.25 grams) will increase magnesium by about 12ppm, meeting the minimum requirement for healthy fermentation.

Be aware, concentrations over 50ppm will give the final beer a sour-bitter taste and levels higher than 125ppm could act as a laxative. So, be careful with this one!

Sodium

According to a 2010 report in the International Journal of Wine Research, salt actually has a positive impact on the fermentation process. So it’s good for yeast as well!. More importantly, a bit of salt (70-150ppm) will accentuate the overall flavors (grains, hops, etc.) of the beer. However, keep sodium below 150ppm to avoid beer that tastes salty (unless you’re making a beer that is supposed to taste a bit salty, such as a Gose). Adding 0.8 tsp. (5 grams) to 7 gallons of brewing water will increase sodium to about 75ppm.

Carbonate and Bicarbonate

Carbonate and bicarbonate could be present in your brewing water, but bicarbonate is most likely the unit you’ll need to adjust. Bicarbonate acts as a “buffer” against pH change. Water with high bicarbonate levels has high “buffering capacity” and is more resistant to pH change.  Conversely, water with low buffering capacity (reverse osmosis water, for example) will have almost no buffering agents and may be more susceptible to pH change during the mash. Depending on the style of beer you’re brewing you may need to increase or decrease buffering capacity, which will be explained below.

Base malts and lighter colored grains lower pH of the mash slighlty. Darker roast, specialty malts tend to lower mash pH a lot. In general, mash pH should be anywhere from 5.2 to 5.6 (measured at least 15 minutes after grain has been added to the brewing water). This means that if you brew a stout with reverse osmosis (RO) water, mash pH will likely drop below the ideal range due to the low buffering capacity of the water and the acidity of the dark roasted grains), the resulting beer tends to take on a harsh “grainy” taste with less body. To counteract the acidity of specialty grains, increase pH by adding baking soda.

The easiest way to reduce bicarbonate levels is to cut your tap (or well) water with distilled water at a ratio of 1:1. This will roughly reduce bicarbonate levels by half. Be aware, this will also reduce levels of other minerals in your brewing water.

Calculating pH increases is more complicated than the adjustments listed above and the use of a water calculator, such as BeerSmith or Brewer’s Friend (an online calculator), is suggested. The easiest way to adjust pH is to brew the beer, measure the pH of the mash (during the brew day) and add a bit of baking soda or distilled water for the next batch. 

Sulfate

The presence of sulfate in brewing water does several things to the final product. Adding moderate amounts will accentuate hop character (namely bitterness) and will also make the beer taste a bit more dry.. However, high amounts (above 400ppm) of sulfate is said to actually reduce hop bitterness. To increase sulfate sulfate, add gypsum. Adding 2.5 tsp. (or 10 grams) will increase sulfate levels of RO water by just over 200ppm. However, it will also increase

Chloride

Chloride, not to be confused with chlorine, which we will discuss next, is another common addition to brewing water. If you’re looking to boost the malt character of your beer, pay close attention to chloride content. The easiest way to increase clhoride is by adding NaCl, which you will probably recognize as table salt. Make sure to add non-iodized salt that is free from any anti-caking agents). Adding 0.8 tsp. (5 grams) to 7 gallons of brewing water will increase chloride to about 115ppm. Note, it will also increase sodium by about 75ppm.

Additional Concerns

There are a handful of heavy metals and other contaminants that are undesirable ingredients in brewing water. We recommend picking up the book Water - A Comprehensive Guide for Brewers for more information. However, there is one common contaminant that we will discuss here, which is chlorine.

Chlorine and Chloramine

Some water municipalities treat their water with a chlorine (or chloramine) solution to help kill off any bacteria or other bugs that might have infiltrated the system. You can probably tell if chlorine is present in excessive amounts by how your water smells. As you can guess, that’s not going to lend any nice flavors to your beer.

Water with elevated chlorine can result in beer that tastes slightly medicinal, or like band-aids. The good news is that chlorine is generally easy to remove. Here are the three most common options for doing so.

1. Add water to the brewing kettle 24 hours in advance and allow it to sit, uncovered. Most and potentially even all of the chlorine will evaporate. Note, this method does not work for chloramine.
2. You can buy something called potassium metabisulphate, also known as campden tablets, at your local homebrew shop as a way to counteract that effect. Add 1 tablet per 20 gallons. For a 5 gallon finished batch (with 7-8 gallons of starting water), you’ll need just under half a tablet. This should neutralize most of the chlorine (and chloramine) in your water in about 20 minutes.
3. You can also filter your water to remove these compounds but be aware that chloramine is more difficult to filter than chlorine. Most basic filters will remove chlorine. More effective filters may be needed for chloramine.

Example Brewing Water Adjustment

Assuming you’re using reverse osmosis water that has been completely stripped of minerals AND has perfectly balanced pH (7), here’s how we’d adjust our water to brew a Dry Irish Stout with the following targets, which is the historical water profile for Dublin, Ireland.

Target brewing water chemistry results:

• Ca - 110 ppm
• Mg - 4 ppm
• Na - 12 ppm
• SO4 - 74.6 ppm
• Cl - 48.2 ppm
• HCO3 - 280 ppm

Using the Brewer's Friend water chemistry calculator, we calculated the optimal brewing salt additions to be 8.4 grams of baking soda, which will bring up the alkalinity of the brewing water, which is going to be the most important thing to do for this beer (as low pH will be a concern due to the high volume of darker, acidic, grains), 4 grams of gypsum, 3 grams of calcium chloride, and 1 gram of Epsom salt. These additions produce the following results.

Target brewing water chemistry results:

• Ca - 110 ppm
• Mg - 4 ppm
• Na - 12 ppm
• SO4 - 74.6 ppm
• Cl - 48.2 ppm
• HCO3 - 280 ppm

These additions would bring us closer to our targets but still off by more than 75ppm for some the sodium. Is that OK? Yeah, definitely. Again, the best thing we can probably do for this beer is to increase the residual alkalinity, which we’ve done with the baking soda. This also happened to increase the sodium, but that’s fine. A bit of salt will only likely bring out the flavors and make this beer taste better. Also, kept increasing the calcium chloride number until the chemistry calculator told us that the beer would be bitter (which fits the style) but not "highly bitter." Either would be OK, but we preferred the former.