I made a homebrew today using tap water, and to my horror I realized I forgot to add the campden tablets to neutralize the chloramine. About 5 years back I made the same stupid mistake, and fermentation never started up, rendering my homebrew a total loss. Can the chloramine levels be great enough that it actually prevents yeast from taking off?
Not likely. The presence of chloramine should not impact the reliability or speed of fermentation. The primary reason you want to avoid chloramine is if you are mashing or steeping grains (not just using extract) it will react with compounds present in the grain and produce precursors that will yield harsh band-aid or medicinal flavors in the fermented beer.