I do biab method brewing but my kettle is only so big I can only do partial volume boils. I cool my wort then put it in a bucket or carboy and fill it with bottled water till I hit my OG. I have been doing this for about 10 batches now and have not had a problem yet. What are the cons of doing this method? In the future I want to get a bigger kettle so I can do full volume boils, but for now my set up works.