How many times can you reuse the oceans water?



For example, when we drink water, the water gets out back into the ocean when we finish, then we get that water again from the ocean, is there a limit to how many times we can do this?

In: Earth Science

No limit exists with the forces we know now, except for the inevitable heat death of the universe.

Since the ocean is just compounds sitting in a place, we can draw in it repeatedly, assuming only water gets cycled.

As many times as you want. The limit to this is the point at which we run out of the power necessary to desalinate it, which isn’t going to happen until the sun dies, expands and obliterates the entire planet.

The water goes through a pretty well known cycle. Like you say, you use it, flush it away down the drain, and it goes to the ocean.

Then the sun shines on it, and the water evaporates into the atmosphere as moisture, winds blows the moisture over land, it forms clouds and it rains (and snows, etc). All that water in the rain collects in rivers and lakes, and you pump it out of there to drink it again. That cycle is extremely good at renewing the water.

it has been going on billions and billions of times, and will continue to go on for billions of more times. There is effectively no limit on how often this can happen.

If you really want you mind blown: The water you drank today was likely dinosaur piss at one time.

Most things we do with water are no problem. Drinking, growing food, boiling to create steam for various purposes, the water eventually re-mixes with the rest of Earth’s water.

There’s one thing I can think of that actually destroys water — If you use electricity to turn the water into hydrogen and oxygen (electrolysis), the water’s gone.

We don’t do this on large scales (hydrogen’s cheaper to produce from oil or natural gas, and oxygen is easy to get from the air). Hydrogen might one day be used on a large scale as an electric vehicle fuel or an energy storage system. Those applications involve burning the hydrogen in oxygen, which gives you the water back.

So even if we start doing large-scale electrolysis, the only water we’d actually lose is due to the small amount of hydrogen escaping due to leaks, imperfect fittings, or accidents. Or when you let unburned hydrogen out sometimes for maintenance or scrapping at the end of life. Hydrogen that gets into the atmosphere is lighter than the other gases, so it will eventually make its way to the top of the atmosphere and escape into space.

Also I should mention that when the Sun starts to die in a few billion years, it will get hotter and expand a lot. It will probably boil the oceans then. If humanity’s still around at that time, they’ll probably have some pretty crazy technology and infrastructure, and be able to evacuate everyone to other planets / stars.