Water Chemistry

[Michaelangelo]

So I just got the new municipal water report. What are the acceptable levels of chlorine and iron so as not to inhibit fermentation?

The report lists a range of chlorine levels detected between 0.28 -0.77 with an MRDLG = 4

Iron was listed as .07 with an MCLG of N/A and MCL at 1.0

Not a chemist, but learning fast. Any input would be appreciated.

[Mars]

I would suggest doing some fermentations yourself and see how they go.

[Sorghumrunner]

I see you didn't get any feedback. I'm interested in knowing what folks are looking for as well. I'm about to take a water sample for testing, any tips on what tests to request from the lab?

So I just got the new municipal water report. What are the acceptable levels of chlorine and iron so as not to inhibit fermentation?

The report lists a range of chlorine levels detected between 0.28 -0.77 with an MRDLG = 4

Iron was listed as .07 with an MCLG of N/A and MCL at 1.0

Not a chemist, but learning fast. Any input would be appreciated.

[Michaelangelo]

Chlorine and chloramines will kill your fermentation, also check your iron level. We decided to use the RO water for everything just to be safe.

[johnbsys]

The chlorine level in most municipalities is normally low enough to not effect fermentation else you would hear more about it from home beer brewers across the U.S. Not sure about irons effect on fermentation. The chlorine evaporates within 24 hours in most cases. If you place an aerator on your water hose it helps dissipate the chlorine faster.

[delta H]

Chlorine and chloramine can be easily removed (reacted away, technically) by adding sodium metabisulfite. This is standard practice among most homebrewers, and should be done for a couple reasons. Chlorine/amine can react with phenolic compounds in the malt (or other plant material you are mashing) and produce off flavors (ever have homebrew that tasted like band-aids?). The effect of low levels of clorine/amine on enzyme/yeast/stainless is less of an issue but is certainly isn't a good thing and removing it is going to help there too.

Fe is more of a problem for the enzymes in the mash. The primary issue is loss of enzyme activity due to something called Fenton chemistry, which is basically Fe redoxing between Fe2+ and Fe3+ and kicking off reactive oxygen species (hydroxyl radicals, h2O2, etc). There are some easy ways to get rid of Iron but most will be issues for the calcium cofactors required by amylases (Ca2+ and Fe2+ bind the same sorts of chemical structures). I could go on at length about options, but the best is just to have (or make) water very low in Fe. If you can't manage that, there are some tricks relating to lowering the oxygen content of the mash (Preboiling the strike water just before use will lower the O2 drives reactive oxygen species formation), but in general higher iron means that you will need to mash longer and will be more likely to need to add exogenous enzymes to maximize starch conversion.