OK, you're right. I need to be more careful in what I'm saying, then.
My claim, specifically, is that science does not have a large enough lack of knowledge about water -- or any other simple chemical -- in the specific areas of chemistry or particle physics, to suggest that there is even an unknown mechanism by which extra-molecular information might be stored in such a chemical, "extra-molecular" here meaning any information which wouldn't otherwise be included naturally as a part of that chemical. Furthermore, I'm saying that, in the absence of such unknowns, and given current knowledge of basic chemistry and physics, such hypothetical information storage would violate the already-accepted principles of those fields.
In other words, I'm placing the burden of proof squarely on the shoulders of the people making the fantastical claim, and I'm justifying that by claiming that we have a large enough body of evidence to support labeling their claim as "fantastical".
Now, if this was the 17th century, and I appeared out of nowhere and proclaimed, "water cannot have memory!" -- then maybe you'd have a point. Instead, there's this wonderfully large body of understanding of chemistry and physics which, while incomplete, is not so incomplete as to leave any room for a method of information storage in basic chemicals without contradicting current knowledge. Thus, "water can not have memory."
If you want to press further on this and challenge my assertion anyway, then I present as evidence the entire body of science. Your move. :-) If you can successfully disprove enough current chemistry or physics to leave the door open for any kind of "memory" in water, then there is probably a large amount of fame and acclaim waiting for you.
(And yes, there is some debate about how gravity works. While general relativity does a neat job of modeling gravity, it is somewhat unsatisfying as an explanation for its mechanism. And also, yes, I would be inclined to say that "anti-gravity is impossible", although with somewhat more reservation, because so far the best explanation for gravity is that it is in fact some kind of side-effect of mass on a space-time environment, so "anti-gravity" would require negative mass, which last time I checked doesn't even make sense -- although I haven't been watching the journals as closely as I used to.)