Woo! I'm glad I helped
If it had extra utilities 2, there is a fluid trash can; otherwise... hmm. It sounds terribly manual, but if you have any blocks that can place a fluid source into the world (AA has one) you can have a block placer basically put something like cobblestone over that, just like you would to remove water or lava source blocks. The IE multiblock tank can hold 512 buckets of liquid, and costs 34 iron sheetmetal and 4 treated wood fence normally - that's not super cheap but it might be a good option rather than voiding it?