pre-filling vs. topping off

I thought I had read somewhere that one can add water - sterile, of course - to a sanitized carboy and then top it with a sanitized piece of foil, the day before the brew so that it's ready to go for brew day (wort goes in and it's already at 5 gallons). Is this true?

Does anyone have a preference for pre-filling the carboy with a couple gallons of water vs. topping off with water after the wort goes into the carboy?

Also, Chicago tap water is very good. Is tap water okay to add (pre- or post-wort) or should I boil it to get rid of any unpleasant things which might harm the beer?

Cheers,
JWiC

I'd still boil the water.

You can add the water before you add your wort, but you are running the risk of dilluting your wort down too much, but you can definately do it. You could even chill that water and use it to help cool your wort down. Ultimately I think its better to top off.

Nothing wrong with having water ready a day ahead. I would add water to the wort instead of add wort to the water. If you miss calculate your water needs you can't take it out once you start blending. By adding wort and then topping off with water you can slowly add the water until you hit your intended OG without worry of over dilution. Just make sure to mix well before taking a reading.

Thanks! You're right, I just made a starter this morning and I put foil on the top. I though for some reason, though, I had read a post about sanitizing a carboy the day before brew day and pre-filling it so that all one must do on brew day is brew and then add the chilled wort to the pre-filled/pre-sanitized carboy... I will avoid doing that, however, and chalk it up to a mis-remembering...

Another question but still related.

Both replies at least hint at having the right amount of water. I thought that the total volume should equal 5 gallons. Am I wrong? 2.5 of top-off water + 2.5 partial boil = 5 gallons? Or is this another time for the hydrometer? Does the amount of water I add depend on the gravity of the wort+water in the fermenter?

That's kind of up to you. You definately should aim for 5 gallons if the recipe is designed to give you 5 gallons. You could just ferment your wort without topping off, but you will end up with a stronger and probably maltier version of what you set out to make. AND, you'll only have 2.5 gallons of it. TRY to boil down to about 2.5 gallons then top off to finish with 5. You may have 2.4 gallons of wort and top off with 2.6, etc.... If you are doing extract batches, aim for 5 gallons in the end and you'll be real close to your target. If you start doing all grain and full boils, it gets easier to 'mess up'.

Brewed extract for years and top off water always came straight from the tap. Never boiled it.

Special Hops said:

Brewed extract for years and top off water always came straight from the tap. Never boiled it.

Click to expand...

Lucky you! we get too many chemicals here,& I'm only a couple miles from the shore of Lake Erie. And in a newer home. Thus the spring water. Works way better,no more off flavors from chloramines,etc.

Yeah, Chicago has pretty good drinking water. What's odd, though, is that water from my kitchen faucet smells very chemically (chlorine?) but water from my bathroom tap just steps away smells "normal."

Thank you, guys, for all the replies; and quickly at that!

I would say I'm in the category of homebrewer who likes to be pretty exact and know the science behind the brewing. On the other hand, if I get pretty close to what I'm going for without being perfectly exact, I'll live. Should still be potable and enjoyable!

Thanks, again!

Cheers,
JWiC

Always top off. You can't count for the exact amount of lost fluid to boil off. So it's always best to top off than start with water in your fermenter. Another reason is because you can then add the right temperature water to hit your intended starting fermentation temp. If it's too cool you can add warm/hot water. If it's too hot you can add cold water.


Rev.

I use cold water straight from the tap. Usually as the boil's finishing, I fill the bucket about half full with cold water just from the tap. Then I pour in the wort, and top the rest up with more cold tap water. Double benefit of tap water being very well aerated, and cold enough that the wort gets down to pitching temps almost immediately