i have noticed several times people saying that their casein doesn't mix and stays clumpy. i have always used reverse osmosis water, then one time i switched it up and used tap water and my shit was mad clumpy. i tested back and forth a few times and it was the tap water making it clumpy but it was perfectly fine in reverse osmosis. to branch out, i have also tried 2 different refrigerator purifiers, one didn't clump it up and the other did. so those of you who have half jugs of casein lying around that you stopped using because it was clumpy, try some bottled water or something and report back if it works or not.