
I had made a 5 grain Bourbon with 60% corn, 10% rye, 10% malted wheat, 10% malted barley, 10% oat. I kept the grains then added a half batch using 90% corn, 10% oat (using emzymes) then punched this up with water and sugar to a 10% wash I was going to use for a neutral.
I distilled this on a pot still with thumper 3 times. First as a fast strip run I could run fast without a lot of worry of slight puke or some corn grist making it's way through the still as I ran it dirty down to 15%. Everything but the forshots was rerun. Second run was another cleanup run ran faster but not as slow as a typical spirit run. I ran this down to 15%. I used all backset for another mash. I "nuked" the first 1/3 of the run in the microwave to 165 F to "blow off" the heads.
I then reran this a third time very slow (drip, drip, drip). I kept everything down to when it started getting cloudy (tails). I did keep running the tails to save as feints for another run.
Next I took each quart jar and nuked it to 150ish F, let it cool down, put on lid and stuck it in the freezer. Did this for every jar. Then I ran each jar through charcoal. I repeated the nuke, freezer, charcoal filter 3 times.
So I distilled 3 times or 6 times if you count the thumper like column guys count plates.

I'm using this for marinates I'm preparing for the holidays.
Now where it gets interesting and getting to my question. I took some store purchased spring water and proofed it down to 40% to make a vodka from my "neutral spirits" just to see how well it would turn out. I added 5 drops of glycerin to the 3/4 quart jar. I whipped up a dirty vodka martini which is my favorite way to drink vodka.
I had chilled my glass and the vodka I made. It went down so easy I thought I goofed the proof so I rechecked it. I thought maybe I proofed it down to 40 vs 80 or something because it was just too smooth. It was 80 proof, 50% ABV at room temp.
It was too smooth. Now normally this wouldn't be a problem.

But it was too smooth for a martini if that makes any sense. It actually lacked what store bought spirits have taste wise and the martini while refreshing didn't have that "Gray Goose" taste I'm accustomed to.
So now my question after the big lead up. Since 60% of what we drink in the finished vodka is water and only 40% is alcohol what do you guys use to cut it with? Have any of you guys found any particular bottled water to be better than other? Would a bottle of Fiji, or perhaps some type of mineral water add that missing component most people are used to in their vodka?
Has anyone found any "magic" water that works best for dilution when they make a vodka like spirit?