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Where does your water come from?

Thames Water Employee

Where does your water come from?


We don’t blame you if your first thought is ‘my tap’. Whether you’re popping on the kettle or hopping in the shower, it’s easy to take for granted that water’s always right there when you need it.


But every drop of water embarks on its own journey before it flows through your pipes. This journey could take billions of years, meaning your humble glass of water could be older than you, the dinosaurs or even the Sun.


In fact, scientists reckon that as much as 50% of the water on earth could have come from interstellar space before the Sun burst into being.


That’s pretty mind-blowing, if you ask us.


Are you ready to channel your inner raindrop and join water on its wild and wonderful journey from the edge of the atmosphere to the depths of the earth? Read on…


Raindrops are falling on your head

Heat from the Sun causes water to evaporate from our rivers and oceans, rising upwards as water vapour. Clouds form in the sky when this rising air cools down quickly, causing water vapour molecules to clump together.

While these clouds look light and fluffy, they’re actually made up of billions of tiny water droplets.


Scientists reckon some could weigh as much as 100 million tonnes – that’s the equivalent of around 40 million elephants hanging out above your head.


When the water droplets get too heavy, they start falling to the ground, and we start reaching for our umbrellas and our wellies, ready to splash our way to work.


It sometimes feels like it’s always raining in the UK, but maybe that’s because we Brits love to talk about the weather. We do have a variable climate, which means our weather can be unpredictable (and it’s getting more and more unpredictable every year).


But did you know London actually gets less annual rainfall than Sydney, the land of sunshine, surfing, and shrimps on the barbie? We get a lot of grey days, but grey doesn’t always mean rain. It’s no wonder that every drop we get is so essential.  


Going with the flow

Rain isn’t just for singing in – it’s for drinking, washing and flushing loos, too! 


After rainwater falls from the sky, some flows straight into rivers. We use much of this water to supply our millions of customers around the region. In London, for example, around 80% of the water we use comes from our rivers. In the Thames Valley, this drops to 30%.


So, where does the rest of our water come from? We tap into supplies deep underground, pumping it out of natural sources we call aquifers. Most of our rivers are also supplied by these aquifers, making groundwater our number one water source.  


When it’s colder outside, the ground stays wet longer and more rainwater soaks into the aquifers beneath. This means we rely on winter rain the most. In the summer, most rainfall is used by plants or evaporates straight away.


The fact that we take all of our water from natural sources is a good thing. If you were to dig deep around much of our area, you’d find lots of soft chalky limestone rocks.


When rain seeps through this rock, it acts as a natural filter and adds traces of natural, healthy  minerals like magnesium, calcium and potassium, making our water hard and giving it its own distinctive great taste. Not only that, but some studies suggest that the magnesium in hard water could even be good for your heart health – who knew?


Of course, we can only pump a certain amount of water out of our rivers and aquifers. To care for the environment and local water sources, we also need to make sure there’s still enough left for local wildlife and plants to thrive.


From the planet to your pipes

Turning on your tap takes less than a second, but the natural process behind it can take thousands of years. In the grand scheme of the water cycle, we’re just a drop in the ocean (pun intended).   


With that being said, our role is an essential one because we make sure your water’s safe to drink. We do this by properly cleaning everything we pump out of local rivers and aquifers.


We then supply more than 2.6 billion litres of this water to homes like yours every day. It’s our job to make sure that your water flows straight out of your taps, clean and fresh.


Not only do we use up to 10 different filtering methods to do this, we also test the water at every stage of the treatment process, producing a staggering 2.5 million test results each year. This means our water is actually some of the highest quality tap water in the world.


After that, we pump the water straight into our complex network of pipes and storage reservoirs, which span over 20,000 miles under every road. Then it’s not seen again until you turn on your tap.


From that point on, any water that you pour down your plughole is filtered and cleaned by us, and then safely pumped back into local rivers. And the cycle begins again…


Why is water’s journey so important?

By 2050, there’ll be an extra two million people living in London and the Thames Valley. If we keep using water like we are today, we’ll need an extra 250 million litres of water a day to meet demand in our area.


That’s a scary figure because:

  • We can’t ask the clouds to make more rain.
  • We can’t take more water from our local rivers without damaging the environment.
  • We can’t know for sure what the future holds for our planet.

Our water may have been around for billions of years, but we need to care for it if we want it to last for billions more to come.


The good news is that we can all help to look after every drop.


Find out how you can help to care for water now.