Can I add water during the boil?

[OHIOSTEVE]

I want to get my Ag set up to run a batch. I think I have everything figured out ( as far as HOW to do things but I know I will be learning ten years from now) I do not however have any idea how to calculate the preboil volume on the first few batches as I will have no way of knowing what my boil off will be. Can I slowly add water to the boil if I start getting too low on volume as long as I do not stop the boil? Or would I be better off topping off after the boil even though that defeats the full boil.

 

[-TPM-]

What I do is collect extra running's in a container and if needed (boil off or over) add that.

 

[PT Ray]

I really don't worry about my preboil volume, I'll just top off at the end of the boil if need be.

This really works in my favor. My 10 gallon pot will cover two burners on the stovetop and I used that to do my boil. It's not much of a rolling boil at 6+ gallons but at 5 I'm in business.

 

[Jaybird]

The only thing you’re really going to change is the extraction rate (utilization rate) of the hops because of the change in gravity. If you calculate the rate of extraction based on a starting gravity and you alter that gravity you will in turn alter the utilization rate of the hops. Major issue? Not at all. If I was limited in boil volume because of kettle size and I wanted to sanitize all my water, say 5 gallon kettle and 5 gallon batch, I would do a partial boil calculate for hop utilization based on gravity of boiling wort and add the rest of my water (slowly) in the last 5 min of the boil when I add my finishing hops.
Jay

 

[tcklord]

I wouldn't worry about it too much, go ahead and top off. However if you want an accurate boil off rate you should measure what you add. That way next time you can account for your boil off before you start.