Most organisms depend on water for metabolisms. Even the higher organisms need to maintain their daily water intake. Why water and not something else (for example like H2S)? I know H2S is poisonous for our body but isn't that just because our body is not compatible with it? Is there a possibility that we could have been compatible with H2S and not H2O? What are the factors that prevent this?
One source says,
It's not the most impressive source, but here's another source that has the same theme, with more details:
The water molecule forms non-covalent bondings. It is bipolar and easily 'gets inbetween' other molecules which want to marry by charing their electrons more permanently. This makes water a great dating site where for example aminoacids quickly can try out their fit to many different parts of an RNA molecule. If they don't make good enough covalent bondings, water will immediately be there to separate them until the next one comes along for a try.
Methane (on Titan) is as liquid as water and does transport stuff around. But it lacks the ability to interfer with how other molecules bond. Biochemical processes would be much slower in methane liquid than in liquid water.
Water is also a fabulous solvent; so many things can be dissolved in it. As others have mentioned, the simple abundance of water in the universe may be a factor.
However, I don't know anything about H2S' bonding ability or its power as a solvent.