too much iron in water?

[snipe98]

I have been looking into this and I see where most people say a trace amount of iron is ok and shouldn't produce any off flavors, but how much is too much. I am on well water and I normally use the sink in my garage which isn't connected to my water softener. I have noticed lately that I am getting an off flavor at the finish of the beer. kind of a metallic mucky flavor. I am going to pickup a water test kit that will check my iron ppm tomorrow but just wanted to get a head start and see what everyone on here thought. thanks

 

[ajdelange]

The EPA SMCL for iron is 0.30 mg/L (ppm). For brewing you want 0.1 or less.

 

[kh54s10]

If you put a magnet against a glass of the water and it sticks your iron content is too high for brewing. I set up my brew porch with a carbon water filter (city water) and have great results.

I would at least recommend a good filter.

 

[ajdelange]

An ordinary filter won't do you much good with iron unless you oxidize it to the Fe(III) state first so that it forms the hydroxide (ugly gel which plugs a filter pretty fast). Lets see how much you have first before discussing how to get it down to 0.1.

 

[Hamaki]

I'm still curious about documentation on how much iron is too much. In another thread dannysk said, "... in a medium bodied beer, iron is detectable at bout 0.07 ppm it is fairly strong at about 0.11 ppm and absolutely undrinkable at about 0.15+ ppm... subjective but a good indicator." He said these numbers were based on personal experience working in a brewery. I'd found an article regarding a university study in Spain that reported average iron content in commercial pale beers of .092 ppm iron and .121 for dark beers. These were averages which means that there must be commercial examples with higher iron levels. If the numbers reflect brewing water Fe content I'd expect there to be objectionable metallic flavors in many of the beers tested. Then again, I don't know if all the iron in the university test results originated in the water or if some contribution by malt, etc. could be a factor.

I'm sure my well water exceeds the .3 ppm EPA MCL for iron and probably the .05 for Mn as well (common in my area). I taste & see the effects of iron in my tap water and to be honest I like the taste. I could do without the staining. I do not get metallic flavors in my beer but get a harsh bitterness in some recipes, mainly APAs & IPAs. I'm thinking this may be more related to carbonate but maybe it's an iron or manganese thing. I have many questions - What is the .1 ppm (or .07 ppm or .11 ppm) based on? How was the standard established? Does beer color/gravity/style come into play when determining how big a problem higher iron might be? Is metallic taste the only problem one can expect from high iron? etc...

 

[ajdelange]

The 0.1 number comes from Wildner H., Eisen und mangan in Brauwasser, Brauwiss, 14: 101-106, 127 - 130 1961. This is consistent with what you quoted but it is not a standard - just the opinions of the two writers. In brewing there are many, many factors and if someone published "iron should be less than 0.1" or "calcium should be at least 50" brewers tend to cleve to those numbers and they propagate from book to article to book even though they may be (in the case of calcium at least) inaccurate.

Negative effects of iron on brewing such as hazy worts, 'enfeeblement of the yeast', impaired colloidal stability, and problems with color and flavor have been described.

I don't think iron will cause harsh bitterness. That is usually a result of too much hops, high kettle pH and too much sulfate in the water.

It is pretty easy to get rid of the iron in a small amount of water. Aerate it thoroughly to turn all the iron into Fe(III) and if the pH is low, add a wee bit of lime to get it high enough that the Fe(OH)3 precipitates. Then filter through clean play sand. As you are buying a test kit test before and after and brew identical beers with and without. If removing the iron improves the beer then look into an iron reduction filter. These do what you did manually but often use 'greensand' rather than play sand and use KMnO4 as the oxidizing agent.

 

[Hamaki]

Thanks, aj! Very informative.

 

[snipe98]

ok got the test results and they are high. I left out before that I brew out in a detached garage so in the house I have a softener and have no issues in there but in the garage I am running straight off the well. I do have a standard whole house filter out there and I also use one of those RV filters on my feed line. so I took the sample of water running through both filters as to make sure I am getting the same number as I would on brew day. I got 4 ppm with this water. would never dreamed it would have been that high. now I do use RO water as well I have been mixing it 50/50 I have a few friends that brew in my area and that is what they have always done and just assumed that I would be in the "ball park" with my water chemistry. if I am thinking right with the RO water mix that would put me at 2 ppm or about 7-10 times what is being recommended!!!
1. do you think that this might be what is causing this off flavor I am getting?
2. are the filters that I am seeing that eliminate rust and other particles down to 1 micron going to do anything for me or am I looking at having to do something else.

if there is any other info that I am leaving out that would help please let me know.

thx

 

[Hamaki]

If your results were 4 ppm or 4 mg/L and not 4 ppb or 4 ug/L, then yes, I think that would be a factor. Mr. Delange described a low tech, low cost method of oxidizing & filtering that should help but if you have access to RO water it would probably be easier to use that source & build needed minerals back in.