The quick answer to whether there can be a man-made substitute for water that gives US the same benefits is no, but it's worth elaborating why to get an appreciation for this simple but astonishing molecule and material.

A water molecule consists of just three atoms, and pure water has many, many of those molecules. Many people know the formula for water, H₂O, which tells you that two of those atoms are hydrogen, the lightest of all atoms, and one is oxygen. Probably the main reason that water is irreplaceable for humans and most other organisms is that it is involved in the huge number of chemical processes that are part of and required for life. Even so-called "heavy water", where hydrogen is replaced with deuterium, is not able to sustain the life of higher organisms. They die once a significant portion of the hydrogen of their molecules is replaced by deuterium. (Deuterium contains a neutron and a proton in its nucleus, whereas hydrogen just has a proton; that approximately doubles the weight of the atom because hydrogen is so light; other atoms can add a neutron without that affecting how they can sustain biological processes i.e. life).

Here are some other crucial properties of water, which are really quite amazing to all be packed into such a small molecule:

water is one of the best solvents, especially for things like salts, sugars, and other "polar" molecules

water does not dissolve oils, which is crucial for life - cells separate themselves from the environment, and separate processes and structures within themselves with membranes, which rely on the fact that oils separate from water

solid water has a lower density than liquid water; in other words, ice floats on water. This is the opposite of what is the case for most other materials, but since it means that something like a lake freezes from the top and not the bottom, it has been crucial for the development and sustaining of life.

I read your question as being two questions:

1) can humans make water ourselves?
and 2) can humans use a compound other than water to sustain life?

For the first part, yes, humans can synthesize water. Water is made of two hydrogen atoms and one oxygen atom. However, the molecule H₂O doesn't form just by mixing those atoms together. In fact, the electron orbits must link together, which causes a release of energy. Since hydrogen is extremely flammable and oxygen is high energy and promotes oxidation of other materials (i.e. promote combustion), the two mixed together would cause the hydrogen to spark when the energy from bonding was released. Water would form in that explosion, but an explosion would be caused all the same. To create enough drinking water to sustain Earth's human population, would require a large scale operation that was extremely dangerous.

Instead of creating water, some scientists work on "capturing" water where it already exists, such as from water vapor in the air by condensing the liquid or causing rain through cloud seeding. As to the second question, no, humans cannot rely on a different compound than water. The human body is made up of about 60% water, and every living cell in your body requires water to function.

Despite that Earth is made up of 70% water, only 3% is freshwater and less than 1% is actually available for human consumption. This is why it is so important to use water conservatively and protect lakes and rivers from pollution. While you may think of drinking juice or milk as an alternative, the reality is that fruit tree and cows also need to drink water to make those products. So without water, Earth would not be able to support human life.

Water is one of the most common molecules in the universe. In order for us humans to have a chemical that would serve the same role as water but be something different, it would have to be rarer than water. Additionally, you would need to do such re-engineering of the human animal to the point where it wouldn't really be much like us at all, like a robot or something. Unless your intent is to replace humans with computers by uploading human minds into becoming computer programs, I don't see how you could ever divorce us from water. Water is the solvent of all life, and in requiring water humans are like any other living thing.

I agree that we need water, exactly, to live. Life evolved to live in water, and there's nothing else life can live and grow in. Some scientists wonder if there might be another form of life in a world without water. Steve Benner is a famous scientist who says liquid ammonia has some of the advantages of water, but of course we couldn't live in liquid ammonia now!

Besides normal water, H₂O, there's water with Deuterium instead of Hydrogen: D₂O. That's the only liquid I can imagine where some life might be able to live, some of the time. But someone on the internet says cells can't divide in D₂O, even though it's only slightly different from H₂O.

Here's something about the useful things water does that make life possible:

"Liquid water has many peculiarities which confer special properties. The most important among them probably are the ability to establish hydrogen bonds, a high polarity and a high dielectric constant . In the presence of liquid water, large organic molecules have to manage the conflict between hydrophobic groups and hydrophilic groups.

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