Chloramine concentrations, am I out of luck?

I just started paying attention to water chemistry with my last batch that I brewed yesterday, but in all the excitement of adding salts and acid, I failed to look at the chloramine concentration. I'm brewing with St. Louis water, which the water report states has about 2 ppm of chloramine. I haven't been able to find anything yet that states what concentration begin to start causing phenolic flavors, but this could be the culprit of the off flavors in my first two batches.

These first two were extract batches, and I just assumed the little twang flavor was either from under-pitching, no temperature control, or extract twang, though looking back it could be from chloramines. With doing AG, would heating the mash/sparge water help drive them off, or would a full boil be necessary? I did just bottle my first AG batch this weekend though (chocolate stout), and it didn't seem to have any off flavors at all. I have a NB Ranger clone and American IPA sitting in fermenters right now, and I'm kinda worried these are susceptible to the dreaded phenols.

For those of you who want the short and quick:

What concentration of chloramines is detrimental to beer?
Does heating the water drive them off, or does it need to be boiled? Edit: Just read you can't boil chloramines off. Darn.

From now on, Campden tablets will be going into every batch I brew.

Also, I'm using WLP001 and Pacman, kept around 62*F for the first week of fermentation, so hopefully that'll keep the yeast phenols to a minimum. Would dry hopping the crap out of them help mask the off flavor at all?

Thanks,
Phil

As is the case with so many things in brewing, the answer to most of your questions is "It depends." Some people in some beers seem to get away with no chloramine treatment and others get nailed. The fundamental answer to the question "How much chloramine is too much?" is "Enough that you can taste or smell the resulting chlorphenolic." The thing that one usually notices is a plastic smell. My immediate reaction, whenever I am judging and encounter chloramine, is that the plastic cup has broken and that reaction is based on experiences with older plastics that had a rather strong smell if you cracked, heated or otherwise disturbed them.

No chloramine is a good working level and is easily insured by the use of Campden tablets or metabite in another form.

Chloramine will leave water if it is left to stand long enough i.e. days as opposed to overnight which is sufficient for chlorine. It can also be driven off by boiling but again is harder to get rid of. Just heating water to near boiling and aerating or letting it boil for a few seconds is sufficient for chlorine. To remove chloramine to a safe level takes hours of boiling.

Yeah, I figured it's kinda like playing Russian roulette as to if these beers will be affected or not, especially since the chloramine concentration in public water supply is constantly fluctuating. I'm just doing all I can now to keep the yeast from producing phenols, which apparently react with the chloramines to form chlorophenols. Found this, which is pretty reassuring:

The good news is that the presence of chloramines in your beer is far less deleterious than chlorine. Keep an eye on your yeast activity. As long as the yeast is doing OK, the chloramines levels is probably OK. Formation of chlorophenolics and other chlorinated byproducts are reduced by 98% with chloramines relative to chlorine. That means even if you do leave some of it in your brewing water, it won't be a significant problem.

http://www.picobrewery.com/askarchive/chloramine.htm

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Don't know where that quote came from but I'm not sure I buy it. It is true that chlroamines produce fewer DBPs (Disinfection By Products) than chlorine in a water treatment scenario (which is why they are used) but they are much harder to remove and that's why I question the statement in a brewing context. Given equal amounts of chlorine and chloramine in water and using one of the usual simple treatments the chlorine would be gone leaving the chloramine to do its dirty work even if it doesn't do it as efficiently as chlorine.

Yeasts do not produce phenols (with certain notable exceptions which are maintained for their ability to produce phenols i.e. Bavarian wheat beer yeasts) to any appreciable extent. The source of the phenols that react to form chlorphenolics is the grain and as all grains contain them the best approach is to use metabite (or GAC) to remove chloramine. Either of these will remove chlorine as well.