Virtually all of the outfits flogging wonky wellness waters purporting to be "clustered", "unclustered", or otherwise altered in structure claim that one benefit of their product is to promote "cellular hydration" by allowing water to more easily pass through cell walls. This is supposed to improve health and performance, and even halt or reverse aging.
Some of the sales sites, for example, say that "the perfect shape of these water molecules allows them to slip easily through the cell membranes, carrying nutrients into the cells and carrying waste and toxins out."
This is all deceptive commercial humbug; there is no credible scientific evidence for any of these claims.
It turns out that over 3 billion years of evolution has done an exquisitely good job of accommoding cells to plain ordinary H2O something that no self-styled "inventor", working in his garage, is likely to be able to improve on. Water transport across cell membranes is mediated by "water channels" through which plain, ordinary water molecules pass in single file (that is, unclustered) at a rate of around a billion per second. These channels are made of specialized membrane proteins known as aquaporins. A typical channel along with the H2O molecules inside it is depicted schematically on the left, and as a molecular model image at the right.
In late 2001, the journal Science (v 294, p 2353) published an article that describes in great detail how water molecules pass along the aquaporin channel in a "delicately choreographed dance" in which each molecule is severed from its hydrogen-bonded neighbors as it is handed off to a succession of H-bonding sites on the protein itself. (See summary here.) This should put to death, once and for all, the baseless pseudoscience peddled on the structure-altered water sales sites.
Peter Agre of Johns Hopkins University was a co-winner of the 2003 Nobel Prize in Chemistry for his 1991 discovery of the aquaporin water channel. See this article coauthored by Agre for a more comprehensive discussion of this work and its significance in human health.
Note also that "cellular hydration" is not a commonly-used term in physiology or medicine; virtually all of the Web-browser "hits" on this term yield commercial huckster sites.