Originally Posted by Yooper
Geez, go ahead and top it up to 5 gallons. No need to worry about it. Just do it!
+1 for Yooper's advice. What is the difference adding the water now as opposed to last night? You're just talking about adding water. No reason to be scared.
Additionally, don't worry about the fermentation at this point. Wait a couple weeks and if you're still curious you can open the bucket and take a hydrometer reading. Be patient....
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