High Iron levels in your water can destroy a perfectly good beer. But what role does Iron play in brewing and how do you know if iron levels are too high?
How does Iron affect your beer?
High Iron levels in your brewing water can cause oxidation, leading to off colors and taste. The most common complaint of using high iron water is the off-putting taste that it can create. Some people describe it as metallic or even bloodlike. This is especially noticeable when brewing paler beers.
Iron can also cause brown coloration or harm fermentation at higher levels.
Iron in low levels does have some benefits. One of these is that it is an essential nutrient for yeast. But if the level rises above 1ppm then it becomes harmful.
The other major benefit is that it can help with foam stability. Allowing your beer to have that signature look and texture that a good head of foam provides.
Iron Amounts in your Brewing Water
To avoid the metallic taste or other negative effects of high Iron, it should be in concentrations less than 0.3ppm. Many brewers aim for less than 0.1ppm Iron, because even without the negative taste it can lower the shelf life of the beer due to oxidation.
While some homebrewers use water with iron concentrations above 0.3 ppm, several factors influence whether the metallic taste or discoloration will impact the final beer. The type of beer, whether pale or dark, and the amount of iron that remains after fermentation and filtering are key considerations. However, it’s generally safer to aim for the lowest possible iron levels to avoid potential off-flavors.
Testing your water’s Iron levels
There are a few signs you can use to identify high iron levels.
If any of your plumbing has rust colored deposits or spots on it, this is likely an indication that your water is too high in Iron to be suitable for brewing. Another common sign is that your shower or toilet has a rust-colored red/orange ring in it. If either of these happens, you will need to filter or get your water from another source.
If you are not sure if your water is suitable for brewing, the only way to know is to test.
The Craft Pro DIY Test Strips will let you confirm Iron levels with every batch as well as 8 other essential parameters. This will give you Iron concentrations in ranges such as 0-1 ppm, 1- 3 ppm, etc.
The In-Lab Craft Pro Test Kit will allow you to send a water sample to our EPA-Certified lab and get exact concentrations for your brewing water or any brewing liquid. Because Iron typically should be less than 0.3 ppm, this will give you confirmation while the test strips allow you to spot check your water.
Filtering out Iron
Many household water filters will filter out excess Iron to reduce it to a useable level. This can be an affordable option that will not involve installing a more complex filtration system. Simply look at the manufacturer’s specifications to see if it is rated to remove Iron.
Another method that can be used to make filtration more effective is by aerating the water before you filter it. This will cause the added oxygen to react with the iron (Fe2+) and form Iron Hydroxide (Fe(OH)3) which can be more easily removed by a filter.
Softening your brewing water
Softening your brewing water will remove some iron. But it also has some downsides. While softeners do a fantastic job at removing some of the minerals that we don’t want, they may add too much sodium or affect the water chemistry in unwanted ways. Such as removing too much calcium and magnesium. Some water profiles want lower Calcium and Magnesium levels, so this is based on what style of beer you are brewing.
Reverse Osmosis Filter
Reverse Osmosis Filtration has become extremely popular in the brewing community. This is because it will take your water profile to a blank slate. This is an effective way to remove everything you do not want in your water, but it will also remove everything else.
If you are using a reverse osmosis filtration system, you will need to build your own water profile by adding the minerals back in. If you do not know where to start, you can look at our brewing profiles page to see what many popular brewing cities have as their default water.
Buying Distilled Water
If you do not want to install a filter or have access to one, but your Iron levels are too high to brew with, you can always buy RO or distilled water instead of filtering it yourself. This will be the same process as building back your own water profile with an RO system.
What if my beer still tastes metallic, but my water doesn’t have Iron?
If you’ve tested your water and it isn’t high in Iron, the Iron taste may be from another source. The malt and hops will have some iron in them, but it should not be enough to give your beer a metallic taste.
The most common source of this excess iron will be from the brewing equipment. Beer may come into contact with several pieces of metal equipment during the brewing process and any one of these could impart excess iron if it’s not cleaned properly or of low quality. If any of your equipment has visible rust, that is likely the cause.
Another potential source is bad packaging. If you are using bottlecaps or cans that have surface rust they will infuse the beer with metal that can leave that off-flavor.
Conclusion:
High iron levels in brewing water can lead to undesirable metallic flavors, off-colors, and fermentation issues in beer, especially in lighter varieties. While low iron levels are beneficial for yeast nutrition and foam stability, concentrations above 1ppm are harmful. Brewers typically aim for less than 0.3ppm to avoid these negative effects. Signs of high iron include rust-colored deposits in plumbing or test results showing elevated iron levels. Filtration methods like household filters, reverse osmosis, or using distilled water can help reduce iron content, and rusty equipment or packaging may also contribute to off-flavors.
