IIRC, he stated she didn't even drink water and then said I don't know how she did it.
OK, I went back and listened again. Brad doesn't specifically state she doesn't drink water. He does say she doesn't drink Gatorade.
AS: Did she typically drink water or gatorade or anything before she went for a run?
BC: She doesn't drink gatorade, we don't even have Gatorade in the home. Nancy has to run on empty stomach. I don't know how she does it. She can't eat before her runs.
AS: Does she ever drink coffee before her runs?
BC: She may have, I don't know if coffee was part of her regular routine to drink before she ran.
Then there is more conversation about her coffee, the coffee maker, and Brad's coffee. After that:
AS: Did you see whether Nancy drank any coffee that morning?
BC: I don't recall if she drank coffee that morning.
AS: Do you recall whether she ate or drank anything that morning?
BC: I don't re-, no, uh, neither one of us ate anything that morning
AS: From 4:15 to 6:00 did she consume, to your knowledge, any beverages?
BC: I didn't see her drink, I didn't make a cup of coffee for her for the morning.
So, if she absolutely never, ever, drank anything before she ran, and he's telling the truth, I don't think he would have answered the way he did about coffee, he would have said she wouldn't drink it before she ran. So that leaves open the possibility that she had something: coffee, water, something that is not Gatorade.