Iron in Water

Brewing Processes
1

I’m reading Dave Miller’s Brew Like a Pro and one of the items he states that would make water unbrewable (basically saying if you have this go with RO water) are iron levels anywhere near the threshold level of 0.3 ppm.  He states the acceptable limit of iron (not sure if it was a typo or the figure he actually meant as opposed to the threshold level) at 0.03 ppm for brewing water.  According to my city’s water report, the iron is at 0.3 ppm, well above what Miller said is the limit.  He doesn’t explain why iron makes the water unbrewable, though.  Is it just that it will impart a strong iron taste?  I don’t believe I have detected this in my beer, but maybe my palate just sucks.  My full water report is below if it makes a difference.

Water Report Parts Per Million (PPM)
Calcium         48
Magnesium         38
Total Hardness 90
Carbonate         20
Bicarbonate         15
Total Alkalinity 35
Sodium         48
Iron                 0.3
Sulfate         90
Chloride         44
Silica                 11
Fluoride           1
Phosphate, Tot 0.3
Phosphate, Ortho 0.2
Chlorine         1.2
pH                 9.4

2

Apparently, Miller’s book has mis-quoted the iron value.  The limit of 0.3 ppm is an aesthetic standard that EPA has established as a Secondary Standard.  Those secondary standards are not enforcable by law, but serve as goals for water quality.  In the case of iron, the typical water drinker can start to taste the iron (blood-like) flavor and there is the potential for the iron to cause staining on plumbing fixtures.

The water in this case may not have enough iron to be percieved in practice.  If it still tastes good to you and your drinkers, then its OK.  Just recognize that it might be a problem at the reported level.

3

When I had my well tested the iron was 0.75ppm. The house filter was pretty old at the time, so I know that level has come down a bit now that I change the filter regularly, but it’s still high enough to stain my showers/toilets/etc. Regardless, my tap water tastes good, and I haven’t run into any issues brewing all-grain beer. I think you’ll be fine at 0.3ppm as long as your water tastes good.

4

And there’s always the added health benefits of iron in your beer.

“I’m drinking this for medicinal purposes, I gave blood.” 
“Fight anaemia; drink beer.”
“This is blood-y good beer.”