Can Water Really Be "Wasted"?

Inspired by this thread–can water really be wasted?

When I was in high school I remember a science teacher saying that you can’t really “waste” water because the earth is a closed system, so water is always recycled–it evaporates into the air, which forms clouds, rain, back to the earth, and so on. The reason I remember this oh these many years later is that I had heard about “wasting” water all my life, and had never heard anyone say what he did. But it makes sense! So at the risk of making myself look kinda stupid, is this true?

Is water “wasted” or just recycled? And if it is wasted, how?

Although the Earth is a closed system, heavy tropical rain in one area is of no immediate benefit to people living in a desert. So yes, when the local water supply is limited you can certainly “waste” the water you have access to.

Water can be chemically converted into hydrogen and oxygen, and of course destroyed in nuclear reactions, but it’s unlikely that on the terrestrial level these things are happening more often than the reverse.

Sources of water can be contaminated “permanently” as far as humans are concerned, and you can lose water vapor to space. You can otherwise lock it up in ways that make it difficult to recover, and certainly you can drain it from various sources faster than the system can refill them.

But ignoring all of these relative nitpicks, yes, it’s true that water is pretty much impossible to “waste” in the sense of permanently removing it from the ecosystem. When folks talk about “wasting” water, though, they usually mean drinkable water, which is easily overused beyond it’s refill rate, and doesn’t always stay drinkable after use (i.e. it can end up in oceans, polluted sources, or unused/unavailable aquifers.

Thanks. This is basically what I understood, but I thought maybe I was missing something. And I imagine making the water drinkable again comes at a cost both to the pocketbook and the environment?

Exactly. It is totally recyclable, but the recycling doesn’t come for free.

Fresh water can certainly be wasted. While it’s true that water is cycled, at any given point in time only about one zillionth of a percent of it is in the form of fresh water. That makes fresh water incredibly valuable and easy to waste.

Retiruclated water can certainly be wasted. The water coming out of our tap didn’t get their from the last shower.

Treated water can certainly be wasted. In developed nations the water coming through the reticulated supply has undergone a fairly complicated series of physical and chemical treatments. That costs a lot of money and running it down the sewer is wasteful.

Groundwater can certainly be wasted. A lot of groundwater has filtered through to its current location over hundreds of years or even tens of thousands of years. It is moving in a rate of a few litres a day, and if you are poring megalitrees a day down the sewer you are wasting it, and it ain’t coming back.

You pay for the water you use. It varies in different areas, of course, but in my area the city bills me quarterly for water usage. That’s all the water that goes through my house - for bathing, washing, flushing, drinking, lawn watering, and the thousand general daily uses. Same for all the farm, commercial, and industrial consumers, who use thousands of times as much water as I do.

That water, fresh, potable water, has to come from somewhere. It has to be piped to my city, then treated, then pumped to my house. All of that requires an incredible amount of infrastructure to build and maintain. A lot of it is lost along the way because of evaporation and old and leaky pipes. The latter is a huge problem nationwide.

Yes, the water originally comes from the sky. It does so everywhere. And yes, that water is part of a worldwide system. Every water molecule has been around through eternity.

And so what? It still has to get to my tap. Every step that diverts it along the way makes it that much more difficult to get it out of my tap. And I live in an area with abundant fresh water rivers and lakes. In much of the U.S. water is being taken out of underground aquifers. When those are empty, it will take geologic eras to refill. Emptying them sooner than necessary is he very definition of waste, even if those molecules can still be found somewhere on earth.

Water can’t be lost, in that sense. It certainly can be wasted, and in a zillion different ways. We will find this out, and in our lifetimes. IMO, it’s as big a looming crisis as global warming and the end of cheaply available oil.

Under natural condition they certainly are. Most of the oxygen that you are breathing is the direct result of the destruction of water. All the world’s fossil fuels are the result of the destruction of water. All the plant biomass is the result of the destruction of water.

Because photosynthesis destroys water, and because is orders of magnitude more reactive than water, photosynthesis destroys water on an appreciable scale.

While the teacher was correct that the amount of water on earth stays the same, I would have argued with him because “waste” is a terrible word to use in this context. By his logic, you couldn’t waste money because the of overall amount of money in the world doesn’t change just because you flush $1000 down the toilet.

Hmm, good point. My counter is that oxidation (burning) often produces water as a byproduct: it’s a significant component of car exhaust and wood smoke (beyond the water already in the wood), for example. So there are two common reactions competing against each other: oxidations creating water, photosynthesis destroying it. I have no idea of the relative rates of these processes. I’d guess photosynthesis would win.

One indicator of this would be a change in ocean volumes over the past few billion years, but I can’t find a reliable cite for whether it’s changed (except for melt-related issues) or how much. The main consensus seems to be that we can’t reliably estimate it (total ocean volume) even now, much less historically.

In either case, it’s not true that “Every water molecule has been around through eternity.”

The key point, I think, is that the fresh rainwater making cabernet grapes succulent (or blended with soap bubbles in your erotic bath!) is worth far more than after it’s mixed with poisons and travels through sewage channels.

Assuming that “zillionth” is smaller than one, and that iceberg and glacier water is considered fresh, I doubt this statistic (though agreeing that fresh water is valuable). (We’ve long heard of towing icebergs to water arid lands; is that day coming soon?)

While Googling to determine whether “zillionth” was an underestimate when ice is excluded, I found this page which seems to give some quantitative facts about freshwater (though images are blurred).

When it is mentioned that “water was wasted” because someone didn’t install a low-flow toilet, people get this picture as if there was some globally defined amount of fresh water that we all have to use wisely or it will be “used up.” The reality is that it is very location specific.

Many water conservationists rabidly expect all people to perform efforts to protect every last litter of fresh water. That may be necessary in Arizona, but completely not necessary in Canada. Have you ever looked at a map of Eastern Canada? They are practically drowning in freshwater and it gets renewed quite well. The idea that somehow using low-flow showerhead in Quebec or Minnesota is somehow going to help save the world’s freshwater supply is ridiculous.

It is wasted in the sense that the water coming out of your faucet had to be collected, treated, and distributed, all of which takes money and resources to do. Even if it gets recycled, it must be collected, treated, and distributed again. This is reflected in your monthly/quarterly water bill.

It is also wasted in the sense that it’s not available for other needs. If you use a lot of water, you contribute to the requirement for increased infrastructure and/or the tapping of additional water sources to meet everybody’s needs. New aquaducts, wells, pumps, water towers, reservoirs, treatment plans, and so on. Likewise, there are some hard limits in place. The Ogallala Aquifer may become unusable in the next few decades, and the Colorado River dumps very little water into the ocean now because most of it is being used for other purposes (mostly agriculture).

Places like the Great Lakes states aren’t going to run out of fresh water supplies any time soon, but the fact that sanitary municipal water isn’t free means that it’s wise to not be wasteful in those places, too.

Thanks for all these great answers. I’ve actually been wondering about this for years. I suppose I could have googled it to try to figure it out, but the responses here are so clear and varied–it’s really interesting.