Water cycle by Hero Labs

Can You Recycle Water?

04 March 2022 | Facts & Curiosities

Crazy facts about the water cycle

Over the past few decades, it’s become increasingly clear just how important it is to reduce, reuse and recycle everything we have if we want to protect our precious planet. What you might not know is that Earth itself has been doing a spot of recycling for about 4 billion years now – a never-ending loop of water recycling called the water cycle, that spans three states of matter, bends more than a few laws of physics and is responsible for most of the weather on Earth.

4 billion years is a staggeringly long time. Let’s take a moment to try to visualise that.

Spread your arms as wide as you can to represent 4 billion years from left to right. From your furthest left fingertip to your right elbow, life on Earth is nothing but primitive bacteria floating around in boiling, sulphurous lakes (sounds fun). The dinosaurs start to appear somewhere in the middle of your right palm, and are gone by the last knuckles of outstretched right hand. The whole story of man would fit in less than the thickness of one nail clipping, and all of organised society from the Babylonians to the Beetles would disappear in one light stroke of a nail file. Kind of blows your mind.

The water we have on Earth now is the same water we’ve had for all that time. It’s the same water that T-Rexes, Pharaohs and your great-great grandpa drank. We don’t lose or gain water – it just moves around in a never-ending loop, from solid to liquid to gas and back, from high in the air to way below the ground. It’s called the water cycle, and here’s some crazy facts that you can “recycle” to amaze your family and friends.

Ancient Aqua

As far as we know, the water on Earth is older than life itself by a good few million years. Our best guess is that water arrived on Earth on ancient asteroids as ice around 4.6 billion years ago, which definitely sounds more like something from the plot of a Hollywood movie than the origin of your humble cup of tea. Some very smart people, including a collaboration between scientists at MIT and NASA, are even convinced that life arrived here on those very same asteroids from… somewhere else. Nobody really knows, but it sure does make you wonder!

It’s a State of Being

As water goes through the water cycle it takes on many forms. It can be solid, like ice; it can be gaseous, like steam or water vapour, and it can be liquid, like… water.

In moving between these forms, water performs some pretty crazy party tricks:

  •  It can sublime, meaning it goes straight from solid to gas without passing through the liquid stage in between. Most substances can only sublime under extreme conditions – like dry ice, which needs to hit minus 78 degrees C, or the wonderfully named chemical “Buckminsterfullerene”, which can do the same if you heat it up to 500 degrees C. Many other materials will only sublime in a vacuum. Water does it in nature every day, from ice straight to water vapour, like it’s no big deal.
  • It gets bigger when it should be getting smaller – and smaller when it should be getting bigger. Solids are solid because the particles in them are very close together, tightly packed into a… solid. That means that almost without exception, solids are heavier and smaller than their liquid friends. But not water – when you freeze water, it forms a crystalline structure that actually pushes the molecules further apart, making it expand and do the opposite of almost every other substance on Earth. This is why ice floats on water, and also why ice makes your pipes burst (and why you need Sonic to stop that happening!)
  • It also moves energy around the planet in what’s thought to be the largest transfer of energy on Earth. Heat from the sun reaches us as radiation, and although some of it falls on land the vast majority of it is absorbed by the ocean and distributed all over the world. Without this process we would have much more extreme temperatures and most of our world would be uninhabitable.

Chilling Out

When you’ve been around for four billion years, what’s another ten thousand? Within the water cycle there’s something called reservoir residences, meaning places where water hangs around for a while before moving to the next stage. Up in the atmosphere, water doesn’t hang about – the average molecule lasts just 9 days before it falls as rain.

In rivers, it’s two to six months; in lakes, from 50 to a hundred years. Water in the oceans has normally been there for around 3,200 years, and deep groundwater can easily have sat still for 10,000 years (AKA “fossil water”). But the champion of chilling out is Antarctica, where the average water molecule hasn’t moved for 20,000 years and parts have sat still for 800,000 years. Puts waiting for the tube into perspective, I guess.

Told You So

In the 1960s and 70s the first satellites were launched, and for the first time we could see the Earth from space and get a bird’s eye view of our planet’s processes. This allowed the very smart people at the World Climate Research Programme to chart and follow the water cycle at a global level for the very first time, and confirm the complex coupling of water and energy as they flow around the globe.

What might surprise you is that this confirmation was a good few thousand years in the making. As early as 962 BC, Hebrew scholars reasoned that water must “returneth in circuits” because the sea “never filled up” despite being constantly fed by rivers. The Ramayana, a Hindu epic from 400 BC, describes the sun heating water for it to fall again as rain; Plato and Aristotle of ancient Greece talked about water moving in a closed cycle and even described how rain could “percolate” down into underground lakes.

Renaissance scholars followed rainfall to rivers and wrote about underground springs; Leonardi da Vinci speculated that water and energy cycled around the planet, calling it the “great vehicle of nature”. By 1666 the French scientist Pierre Perrault was describing the complete water cycle in much the same way as we understand it today. So perhaps we oughtn’t to give the boffins at NASA too much credit for confirming what humanity had long suspected – water flows in a never-ending cycle!

If the world recycles water, why conserve it?

While the total amount of water on Earth is constant, the population has exploded. Every year the number of people competing for water for drinking, cooking, bathing, cleaning and generally being alive goes up by another fifty or sixty million, while the supply stays more or less the same. To compound matters, most of the water on Earth isn’t actually fit for the purposes that we humans tend to want it for.

About 97.5% of water is salty, so drinking it is right out (it actually removes water from your body), as is agriculture and most other applications. Just 2.5% of water is fresh, and only about 1% of that is in places we can get at it, with most locked up in glaciers, the polar icecaps and deep underground – so in essence, only about 0.007 percent of the planet’s water is available to fuel and feed its 7.5 billion people. When we talk about water conservation, we’re really talking about appreciating how valuable and important water is, and trying to make sure there’s enough to go around for all 7.5 billion people (and counting) – and that there will be in the future, too.

Water really is one of the most precious substances on Earth, and that’s why we at Hero Labs are on a mission to make water waste a thing of the past. If this article has inspired you or made you think, you could jump into our 12 Easy Home Hacks to Save Water, or think about fitting a smart water meter to reduce water waste, avoid unexpected bills and protect your home from leaks.

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