Is it possible to obtain antiwater from antihydrogen and antioxygen atoms? And how is its property w.r.t. the ordinary water?
Research has created antihydrogen, and that is about it for the present as far as antimatter in bulk, which one would need for antiwater..
Scientists in the US produced a clutch of antihelium particles, the antimatter equivalents of the helium nucleus, after smashing gold ions together nearly 1bn times at close to the speed of light.
They were gone as soon as they appeared, but for a fleeting moment they were the heaviest particles of antimatter a laboratory has seen.
If you look at the nuclear binding energy plot, oxygen needs a lot of antinucleons to materialize. Present research has just seen antihelium.
Anti-matter is a lot less exciting than you probably think. If we could magically change all matter to anti-matter by waving a magic wand then it would make almost no difference. The anti-Dirk could drink an anti-glass of anti-water in exactly the same you drink a glass of water. The anti-water would have the same density, boiling point, ability to dissolve anti-salt and so on. Even looking in greater detail the electronic and indeed nuclear spectra would be identical to water.
We have never made anti-water, or even anti-oxygen, and it will be a long time before we achieve such a feat. However we can be very confident about the behaviour of anti-matter because matter and anti-matter are related by a symmetry called CP-Symmetry that is theoretically well understood and experimentally well tested. There are a few differences due to a phenomenon called CP violation1 but this is only observable in colliders like the LHC, and even then it isn't a large effect. As far as everyday life goes anti-water would interact with other anti-matter in exactly the same way as water interacts with matter.
1 though CP violation is possibly the reason matter exists at all, though that's a question for another day