Yes, water is fine, and plenty of it!

Fruit juice is suggested for its nutrition and bowel-moving properties but also to help provide pleasant flavor for people reluctant to drink/eat something ( like a formula based on charcoal) that has a bland or bitter taste.

If using juice or water, it helps to mix the formula by using a small jar, perhaps 8oz or 16oz, put the liquid in first (but do nit fill, leave a couple inches on top after adding firmula to make it easier to shake) add formula 2 powder, attach lid, shake vigorously, chug drink within a few minutes and then add more water to rinse/drink all the little bits that remain after you chugged, the flax seeds tend to stick to the glass, don't want to waste them, drink it all.