Bru'n Dilution Water Calculation?

[Protos]

Sorry if my embarrassingly n00by question has already been asked and answered on the board, I probably just can't find the correct search terms.
I finally got to learning the Bru'n Water Calculator and now I'm a bit confused about the calculation of the Distilled Water Addition.
If I want to dilute my Liquor with, say, 25% of Distilled Water, should I first distract the same 25% from my initial Tap Water volume to replace it with the Distilled?
Or do I just add the Distilled to the total volume?
I feel that distraction (and then addition) is the correct way, but I'm not sure...

 

[VikeMan]

I'm not a Bru'n Water user, but I'd be pretty surprised if the answer is to simply add distilled water to the total water volume. I can't imagine any software would be set up that way.

 

[Protos]

I was thinking the same way but the cells on the last sheet (5. Adjustment Summary) confused me. The Total Mash Water Vol cell shows the total volume I planned for mashing PLUS the dilution volume in an adjacent cell Mash Dilution Vol. It's not obvious from the interface if the Dilution is included into the Total Mash Volume or should be added separately. Then more the sparge water part states specifically that the dilution is included into the Total Sparge Water Vol. result. Why then the dilution is shown separately in the Mash water part, unlike in the Sparge water part? That's what confuses me.

 

[ScrewyBrewer]

@Protos when using the total brewing water for both mash and sparge, the brewing water consists of 25% dilution water and 75% tap water.

When treating brewing water for mash only, 25% of the mash water is dilution water, and 75% is tap water. Allowing you to treat the sparge water separately.