According to chrisb1 and others, it is best to drink to thirst... so i believe 1-3 cups per day at the 8th day is great. Paradoxically to what we might intuitively believe, the cleanse is more intense with less water.
On the other hand and in partial support of your comment scorpio eyes, pooling together from everything i have read, I believe 8 or so cups per day is better in the first 3 days or so to help more easily flush out the heavy preponderance of toxins in our blood and urine at that stage.
"I don't exercise I don't really drink too much water just maybe 1 8 oz bottle per day. I do weigh myself the same time everyday.-when I first wake up 20 minutes after I pee. I don't have any underlying conditions....Its very frusterating. I hope it changes tomorrow."
As for my 2 cents... if you are ingesting nothing besides an 8 oz bottle of water per day and nothing else (this amount of water would add a half pound), and if you urinated at least that amount since your last weigh in, and knowing that your body has to be burning something to survive (fat for fuel)... this constitutes a decidedly proven forumla for going down, not up... i can't imagine it being anything other than the scale giving you inconsistent readings.