[mcw74]

When topping up my fermentor to 5 gallons after adding my wort from an extract boil, is it necessary to boil the tap/well water?
I have been adding water straight from the tap for years and haven't noticed off flavors or other signs of contamination, but surely I'm adding microbes (while taking such care to sterilize all equipment throughout the process!).

[denny]

I never boiled my well water when I was topping up.  I knew it well enough so that I didn't worry about it.  Sounds like you've been fine, so I wouldn't worry about it.

[ipaguy]

I boil my well water in quart canning jars & seal them up.  Doing a dozen at a time gives me enough make-up water for several batches.  I can also refrigerate a few of them to get down to a lower pitching temperature than I can get with my immersion wort chiller.  This may not be strictly necessary, but I figure that it's impossible to be too careful about sanitation.

[tomsawyer]

I use my tap water, its from a municipal treatment facility.  Never had problems with it.

[tschmidlin]

My concern would be with the chlorine in most water supplies, but since you haven't noticed a problem I wouldn't worry about it.

[euge]

I's not something I do all that much these days, but straight out of the tap has always worked for me. As with all things brewing you have to satisfy your own comfort level. Makes you uneasy- don't do it.