Why Water Filtration Matters for Beer Brewing Water

Posted by
John Woodard on July 31, 2020

Water is the most common component of beer, and one of the greatest influences on the beer’s flavor. Historically, bewers used the water locally available to brew their beer, leading to distinct regional flavor profiles emerging around the globe. The water of West Germany’s Dortmund is very hard and rich in calcium, sulfates, and chlorides. The small coal-mining town’s golden pale lager is now internationally heralded for its distinguishing crisp, hoppy flavor, originally bestowed on it by the Dortmund water. The nearby Czech city of Plzen had very soft water that is low in sulfates and bicarbonates. The low alkalinity of the Plzen water created the mellow-flavored light malt known as Pilsner.

With the advance of time, brewers learned that curating the quality and make-up of their water could cultivate unique flavor profiles for their beers. Water filtration systems like reverse osmosis have provided brewers with a stable starting point, from which their creativity can flourish and their recipes can shine. From establishing consistency across batches to mimicking the water quality of famed beer regions halfway across the globe, water filtration gives beer brewers extensive control over taste and the ability to innovate. 

How does water affect the taste of beer? 

Since beer is around 90% water, it is natural that the quality and composition of the water will have a dramatic impact on the beer’s flavor. There are three elements of water that will affect the taste of the beer: mineral composition, pH, and alkalinity. The water’s hardness and mineral make-up will impart flavor and influence the fermentation process. The pH encourages enzymatic action in the mash and fosters the proliferation of yeast during the fermentation stage. Alkalinity creates a buffer to protect the pH from fluctuation throughout the brewing process, making sure bacteria is unable to grow and stripping excess tannins from the beer. These three factors are inextricably linked and work in tandem to guide the taste and color of the beer.

The hot water steeping process, known as mashing, initiates the brewing process and prepares the barley for fermentation. During mashing, crushed grains are hydrated with hot water, which creates a thick mixture and activates enzymes in the malt. These enzymes, namely alpha-amylase and beta-amylase, convert soluble grain starches into fermentable sugars. This fermentable liquid, called the wort, is a combination of proteins and carbohydrates that will influence the malt, mouthfeel, and body of the brew. When the wort is ready to be fermented, it is anywhere between 80-90% water. Though the wort will extract flavors and aromas from the hops, it is only able to do so by being boiled in water. Water is essential to these flavor profiles developing. The enzymatic action transpiring in the mash is entirely facilitated by water and the mineral content of the water. Water is the foundation for the process of brewing beer as a whole.

beer brewing water mash

How do minerals in the water affect the taste of beer? 

The minerals present in the brewing water will dictate the flavor profile of the beer. Water hardness, a measurement of the total levels of dissolved calcium and magnesium, imparts a strong hoppy flavor onto the beer, as the hops cling to calcium ions. If chloride is in the water, it gives the beer a rich mouthfeel. Sodium, sulfates, and carbonates all act to influence fermentation, the mash, and the taste.  The presence (or absence) of these ions each transmit unique flavor characteristics during the brewing process. However, is essential to use them deliberately, as too great an amount can cause unpleasant and overpowering tastes. 

The mineral ions also work in conjunction with the pH and alkalinity throughout the brewing process. Carbonates and bicarbonates stabilize the pH level during the mashing. If there is too much chloride present in the brewing water, the fermentation process can be hindered as chloride will destroy the yeast. This is why precision and attention to detail is integral to any brew, and all the more reason to have a thorough understanding of your water’s composition before you use it to brew. 

Ions in brewing water: 

Calcium (Ca+2): Calcium, a mineral found in high concentrations in regions where groundwater passes through rocks like limestone and gypsum, is one of the two minerals that make up water hardness. While hard water is a nuisance for a homeowner, it can greatly behoove a brewer. Calcium is preferred by many brewers in their water because it lowers the pH during the mashing process, precipitates proteins during boiling, and is a yeast nutrient. Calcium also improves the clarity of the beer. The recommended range of calcium is between 50 mg/L and 150 mg/L. 

How to raise calcium levels in brewing water: 

    • Gypsum 
    • Calcium sulfate
    • Calcium chloride
    • Hydrated lime

Magnesium (Mg+2): Magnesium, the other component of water hardness, is of less importance to brewing, but nonetheless a critical ion to have present. Magnesium is a yeast nutrient, and many brewers strive for around 10-30 mg/L to facilitate healthy yeast growth during the fermentation process. In moderation, magnesium accents the flavor of the beer, but if the brewing water has levels above 30 mg/L it will make the beer taste sour and acerbic.  

How to raise magnesium levels in brewing water: 

    • Epsom salt (magnesium sulfate) 

Sodium (Na+1): Sodium can accentuate the body and flavor of beer, and add the desired sourness to beers like the German gose. In excess, it leaves the beer tasting metallic and harsh. Sodium does little to affect the mash and flavor in low amounts, but it can be toxic to yeast and impede fermentation in too high of concentrations. Usually, the recommended range of sodium is between 10-70mg/L, though as high as 150 mg/L can be used to achieve an intentional salty or sour effect. As with most minerals, your desired beer flavor will predetermine how much sodium you add, but levels over 200 mg/L are unpalatable. 

Since high levels of sodium have such a dramatic impact on taste, you should never use softened water as brewing water. Through a process called ion exchange, water softeners exchange remove calcium and magnesium from the water by replacing them with sodium ions. If you have a water softener to protect your home and appliances from scale, you will need to purify the softened water with a reverse osmosis system before using it in your homebrew. 

How to raise sodium levels in brewing water: 

    • Non-iodized salt or sea salt
    • Baking soda (sodium bicarbonate) 

Chloride (Cl-): Chloride is used to give your brew a full, sweet flavor and rich malty finish. Popular for the complex mouthfeel it lends beer, chloride is usually added to the water in either the form of calcium chloride or sodium chloride. They also promote stability during the mashing process. Chloride is often used in conjunction with sulfate to complement the bitterness of hoppier beers. The ratio of chlorides used is usually dependent on the sulfates, as the two produce opposite flavor profiles in the beer. Deliberate proportions of chloride and sulfate can balance out sweetness and hoppiness within a brew.  

How to raise chloride levels in brewing water: 

    • Calcium chloride
    • Sodium chloride

Sulfates (SO4-2): Sulfates are used to give beer that coveted hoppy flavor. Sulfates bestow the beer with a dry, crispy taste, and as sulfates are alkaline, they can be used to mildly reduce the acidity of the mash. Where a bitterness is desired, sulfates can be used to bolster that flavor profile. The amount of sulfates added varies dramatically based on the desired levels of hoppiness. Where pilsners will strive for between 10-50 mg/L, the celebrated Burton-on-Trent style pale ale uses up to 500 mg/L to achieve its sulphuric smell and sharp taste. Exceeding 500 mg/L is inadvisable, however, as an excess of sulfates in the brewing water can contribute to a laxative effect in the consumer. If the sulfate concentration is too high, it can react with the yeast and create hydrogen sulfide, which will make your brew reek of rotten eggs.  

How to raise sulfate levels in brewing water: 

    • Calcium sulfate
    • Gypsum
    • Epsom salts (magnesium sulfate)

Carbonates & Bicarbonates (CO3-2/HCO3): Carbonates and bicarbonates are essential for any brewer, as they dictate the pH of the mash. Their strong alkalinity buffers the pH from becoming too acidic, resulting in astringent flavors and tannin-heavy beers. They also promote a round, malty taste in the beers, and at high levels can lend a bitterness desired by darker lagers. Since dark grains are more acidic, recipes for dark ales and lagers will usually require 100-300 mg/L of carbonate. Pale ales like IPAs will usually have carbonate levels of 25-50 mg/L. If carbonate levels are not adjusted during fermentation, however, they run the risk of keeping the beer’s pH too high.

How to raise carbonates and bicarbonates in brewing water: 

    • Baking soda (calcium bicarbonate) 
    • Chalk

brewing water for beer mash

Ions that can ruin brewing water: 

Chlorine & Chloramines (Cl2): Chlorine is widely used by municipalities as a chemical disinfectant, protecting the city water supply from bacterial contamination. Unfortunately, chlorine is detrimental to brewing. Detectable in the beer in amounts as low as 5 parts-per-billion, chlorine leaves beer with a palate-ruining plastic taste. When chlorine reacts with ammonia, it forms chloramine, a contaminant even trickier to eliminate from water. Not only do chloramines spoil the taste of the beer, they also prevent the yeast from properly fermenting the brew.   

Iron (Fe+2 & Fe+3): Iron is never a desirable ion in beer. Since iron is the most common mineral found in the earth, many well owners are left with the undesirable ramifications of iron-rich waters. Discoloration, dark orange and brown stains on fixtures, and destroyed appliances all result from even just 0.3 mg/L of iron in the water. Furthermore, iron gives beer an inky aftertaste and interferes with proper fermentation. As little as 0.05 mg/L of iron in your water can ruin your brew. 

Manganese (Mn+2): Any level of manganese greater than 0.01 mg/L is enough to leave your beer tasting metallic and unpleasant. Manganese ions, often found in combination with iron, will affect not just the flavor, but also the beer’s clarity and threaten the health of the yeast during fermentation.  

Nitrates/Nitrites (NO3- & NO2-2): Nitrates and nitrites can enter water through agricultural runoff, animal waste, and pollution. For well owners in farmlands, these contaminants can exist in high levels and present serious health problems if ingested. But, these contaminants are only regulated in water above 10 mg/L by the EPA, and any level above zero risks destroying the flavor of your beer.   

How does pH affect beer brewing? 

The pH of the brewing water has a strong influence on the taste of the beer and is critical to ensuring that enzymatic action transpiring in the mash. The enzyme beta-amylase requires an acidic environment to properly convert the grain starches to fermentable sugars. Yeast thrives in lower pH, meaning the wort will have healthier fermentation. If the mash pH is too high, the beer will have a dull, astringent taste and lose all complexity of flavor. Bacteria can also develop during the fermentation in worts not sufficiently with too high of pH. 

Most water is neutral to alkaline by nature, so it requires the appropriate mineral composition to actuate the acidity. Calcium plays the most important role in facilitating an acidic environment, as it can overcome the malt phosphates alkaline buffer. Carbonates and bicarbonates buffer the alkalinity of the mash, ensuring the pH does not fluctuate too wildly in either direction. The grains themselves are also acidic, which helps aid the enzymes in breaking down the starches. However, the pH of the mash will need to be vigilantly monitored throughout the brewing process. If you are brewing a lighter beer, you will likely need additives to achieve proper mash pH. Use a pH meter to ensure the mixture is remaining in an appropriately acidic range (between 5.2-5.5pH). 

If your mash is too alkaline, there are recourses for you to salvage your beer. Lactic acid, an organic byproduct of milk fermentation, is popularly used to lower the pH of the mash. Lactic acid does not add disagreeable flavor to the mash and can be used to significantly lower the pH level. Phosphoric acid, an inorganic acid found in many commercial beverage products, has the advantage of imparting no taste on beer. Phosphoric acid is less acidic than lactic acid, so it can be a more forgiving product to use when attempting pH adjustment. Buffers and stabilizers can also be added to the mash, which will achieve a target pH level by reacting with the phosphates in the malt. These will increase the calcium and magnesium content, but will hold the target pH without fluctuation and can be pre-measured into the homebrewing water. These are often sold under trade names like 5.2 Stabilizer

What’s the best water for brewing beer?

Since every beer demands different concentrations of hardness, bicarbonates, and sulfates, the best water for brewing beer is one that allows you complete control over the flavor profile. Water with high mineral and metal content will dramatically limit your creative range of expression. To be sure of the ion make-up of your water, request a water quality report from your city or perform a home water test and determine for yourself. City water will inevitably have chlorine and chloramines present in it, both of which can overpower your brew with a chemical taste and spoil your fermentation. If you have very hard water, the range of brews you can explore will be limited, as with calcium levels over 50 mg/L you will not be able to brew lagers.

If you truly wish to perfect your brews, it is wise to have a water filtration system in place. Not only will it improve your beer’s taste, but it will also give your beers greater overall consistency. Perhaps best of all, it’s much easier to concoct a perfect recipe out of water that’s been stripped of all of its mineral and chemical content than it is to try and work around your pre-existing water conditions. 

homebrewing beers

What are the best water filtration systems for homebrewing? 

Reverse osmosis has established itself as the industry favorite for high-purity brewing water. Reverse osmosis systems eliminate over 96% of dissolved salts, solids, and minerals from the water, rendering it a perfect baseline to move forward from. However, there are many options available to brewers seeking to improve their water quality and access a broader range of recipes. Catalytic carbon can remove chloramines from water, which will enhance your brewing water’s taste. Water distillation and deionization both produce water of extraordinary purity as well. Finding the appropriate system for your homebrewing needs is all that stands between you and the best batch of beer you’ve made. 

Reverse osmosis 

Reverse osmosis produces water that is soft, mildly acidic, and free of foul-tasting contaminants like iron, nitrites, chlorine, and chloramines. Using reverse osmosis water provides the brewer with a perfect blank slate, allowing the brewer to craft and execute their own beer recipes from scratch. The high purity of reverse osmosis water eliminates any risk of unwanted flavors and gives the brewer control over every element of the brewing water’s ion composition. As the art of craft brewing became increasingly popular, reverse osmosis water established itself as the preferred choice for brewing beer. From large-scale, industrial brewers to homebrewing, the purity of reverse osmosis water has made it the clear favorite water filtration system for brewers.

Reverse osmosis (RO) reduces contaminants by slowly forcing water through a semipermeable membrane with very small pores. These pores are capable of blocking even the most minuscule of contaminants from passing through while still letting the water molecules pass. The process of osmosis equalizes the concentrations of a solution on two sides of a membrane. As the name implies, reverse osmosis does exactly the opposite. It separates the pure water from all the dissolved organic and inorganic matter in the water. The contaminants are sent down the drain in a solution called brine, and the pure water, called permeate, exits the system and collects in a storage tank.

Brewing beer with RO water is desirable for many reasons. As discussed above, even very low levels of ions can pollute the flavor of the beer you are brewing. Water from a reverse osmosis system is free of any subtle ion presence that could impede fermentation or sour the flavor. In addition, reverse osmosis water allows you to brew whatever recipe you desire. The quality of your water in no way limits what you can brew. Emulating water profiles of famous historical beers is a challenge many brewers love to tackle, like the minerally Dortmunder or Burton-on-Trent’s sulfate-rich brews. With RO water, re-creating these famed beers is achievable. Reverse osmosis also provides consistency across batches. If you are starting from the same base level of high purity each time, any recipe you’ve worked hard to perfect will come out tasting the same every time. 

Learn how reverse osmosis works. | Explore 5 of our favorite reverse osmosis systems

Carbon filters

If you aren’t ready to invest in a reverse osmosis system, a carbon filtration system will provide you with water free of the ruinous chlorine aftertaste. In fact, reverse osmosis uses carbon pre-filters and post-filters to protect the membrane from chlorine and improve the taste and odor of water. Through a process called adsorption, activated carbon filters soak up contaminants from the water. Organic compounds adhere to the extensive surface area of the carbon filter like velcro. Carbon filters are covered in pores that trap contaminants flowing through the water. These pores vary in micron size, and are capable of reducing chlorine, sediments, and VOCs from your water supply. 

Since chlorine is one of the biggest taste offenders in brewing, and since it is so widely used by water municipalities, reducing the chlorine content of your water is the least you can do to elevate your homebrewing. However, as ammonia becomes a more common municipal disinfectant, you want to make sure that your carbon filter is rated for chloramine reduction. Carbon filtration is the best method for eliminating chloramine from drinking water, but removing presents a more difficult challenge. Chloramine reduction can be achieved by increasing your water’s contact time with the carbon filter. Reducing the flow rate at which your water flows through the filter will ensure the adsorption process has ample time to occur, and will increase the chloramine reduction. Chloramine reduction can also be achieved by using a catalytic carbon filter. Catalytic carbon is a carbon blend tailored specifically for reducing chloramine content. Using a carbon and KDF blend can also help reduce some of the heavy metals present in your water, like copper and lead. 

Keep in mind, the mineral content of your water will not be significantly altered by only a carbon filter. This means if you have very hard water, you will still have an abundance of calcium and magnesium after the filtration is completed. If you are content with your water’s mineral make-up for brewing purposes then carbon filtration can be a boon and help remove that unpleasant chlorine taste. But if you are seeking a filter that will eliminate the majority of ions in your water and provide you a blank slate to work with, then carbon filters aren’t the best choice. 

Learn more about activated carbon filters

Water distillers 

Water distillers, much like reverse osmosis, produce water that is devoid of any mineral, metal, or organic content. This is achieved by distillation, a process that mimics the earth’s natural water purification process. Water distillers boil small quantities of water at a time, converting them entirely into a vaporous form. This water vapor is then cooled and returned to a liquid state. During distillation, everything from iron to fluoride is left behind in the boiling chamber and the water emerges devoid of any contaminant or mineral. This water does allow for you to create whatever mineral profile you may desire, and distilled water is used by some brewers.

However, water distillation for brewing is only ideal in homebrewing applications. Water distillers work very slowly, some taking as long as four to six hours to produce a single gallon of water. If you are only producing small batches of beer at a time, a water distiller could support your hobby. If you are running a larger operation, it is unrealistic to rely on a water distiller to provide you with an appropriate amount of water for brewing. Even larger, automatic water distillers work slowly, and cost significantly more than a reverse osmosis system capable of the same output. Though the water they produce is comparable in its remarkable purity, reverse osmosis is far more pragmatic.

For a homebrewer without a high demand, a water distiller is a convenient countertop appliance and can service your needs. They do consume a fair amount of electricity (remember, that water has to be boiled into a total vapor before it can be cooled and condensed.) But, they do offer that desirable mineral-free water that will expand the scope of your brewing options. 

Explore more about how water distillers work. | Discover if drinking distilled water is bad for you


Deionization systems eliminate the mineral content of water through a process called ion exchange. Like water softeners, deionization systems (referred to as DI) use resin beds to facilitate the transfer of ions and eliminate contaminants from water. DI systems trade out positively charged ions (called cations) like iron, sodium, and calcium, for hydrogen ions. Ions with a negative charge (called anions) like carbonates and sulfates are exchanged with hydroxide ions. This results in high purity water that is comprised only of hydrogen and oxygen. 

DI cartridges are often used in tandem with reverse osmosis for applications where only the purest of water is acceptable. Medical and pharmaceutical industries often pair reverse osmosis with deionization, and they are used widely across the cosmetic industry and the electronics industry. Many laboratories also employ the use of deionization to ensure total water clarity. 

For most brewers, reverse osmosis will be a more plausible option. Deionization does provide water absolutely free of minerals and contamination, but DI is primarily used in industrial and medical applications. You can certain install a DI cartridge inline with your RO system, and if you are a large brewery that level of purity may well be desirable. 

To learn more about ion exchange, explore how water softeners work

Ultraviolet purification

There are some steps you should take to ensure the purity of your brewing water that do not involve taste of the final product. If you or your brewery is located on the well, ensuring your water is free of pathogenic bacteria, viruses, and living organisms is essential. Ultraviolet purification (UV) uses ultraviolet light to neutralize any organism extant in the water supply. The UV lamps scramble the DNA of the organisms, rendering them incapable of reproduction and deactivating their potential to transmit diseases. Even if you are using a reverse osmosis system, if you are pulling water from a well or any source that could be microbiologically unsafe, you should have an ultraviolet purification system in place.

Since beer is made to be consumed, shared with friends, and sold to the public, ensuring it’s been stripped of hazardous microorganisms is due diligence incumbent on all brewers. City water suppliers disinfect their water reservoirs with chlorine, but those using a private well must take it upon themselves to safeguard their water from bacterial contamination. To achieve optimal performance from your ultraviolet system, install a sediment filter before the water is treated by the UV light. Bacteria and protozoa can hide behind sediment and the ultraviolet rays have difficulty penetrating water that is cloudy. A sediment pre-filter will ensure no viruses are sneaking their way into your brewing water and craft beers. 

Explore how UV purification works. | Learn more about how sediment filters work.

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