Hi, I’m Martin Appleby. I am a Grantham Scholar in the Chemistry Department at the University of Sheffield. I do a lot of my research at Lord Porter Ultrafast Laser Spectroscopy Laboratory. And it’s my job to think about water.
You may wonder why a chemistry PhD who works on lasers researches water. But my PhD focus is on developing new water purification methods. The technique we are currently investigating uses light-activated metal compounds which absorb energy from the sun (or our lasers) and transfer this energy to oxygen. This makes the oxygen very reactive and it interacts with microorganisms causing damage and hopefully killing them!
If you want to know how much water you use – and you don’t have a water meter – it can be difficult to work out. So here are some general figures about UK water use.
The average person should drink at least 2-2.5 litres of water a day. But drinking water is a tiny fraction of water used in the UK. At home, the average UK person uses 142 litres of water per day and a house of 4 uses around 349 litres per day. And during the COVID-19 lockdown this value increased in some parts of the UK by 25%, to approximately 175 litres of water per day per person.
142 litres is 9.5 times that used by someone who lives in urban Ethiopia, where it is estimated their average daily water use is about 15-35 litres per day (WHO recommend at least 20 litres per day for basic hygiene needs and 50 litres to be adequate).
One of the main sources of water use in the UK is having a shower or a bath. When you take an 8 minute shower you use about 62 litres of water; that’s almost half of your daily water use. And if you have a power shower you’ll use even more water. So a shorter shower is one of the best ways of reducing your personal water usage at home.
But we don’t just use water at home: everything we do has a hidden water cost. What do I mean by this?
The hidden water cost is your total water use based on all the things you do, all the products you buy and use and anything else that could possibly use water (including electricity generation!).
Taking hidden water costs into account it’s estimated a person in the UK uses 3000 litres of water a day. Some say that this is actually 4650-5000 litres for meat diets and around 2000 litres for vegetarian diets.
So there is a big difference between total use and home use. Why?
Only about 3 to 5% of water use happens at home. About 5% is used by industry to provide products and services (all business essentially falls under this category). And the rest?
The rest is from agriculture.
That’s approximately 2700 litres of water a day to produce the food you eat and the drinks you, well, you drink. This is equivalent to showering 44 times per day. And about 62% of this hidden total consumption happens outside of the UK, from water used in agriculture and industry to the water consumed when you go on holiday.
Now, if we again compare UK usage to usage in Ethiopia: 5.95% of their water use comes from the household and 93.69% from agriculture. This shows that the main contributor in water consumption in both countries is agriculture.
It’s estimated that the UK as a whole uses around 14 billion litres of water per day in total. And out of this, 3.17 billion litres of water is lost every day due to leaks. This loss is the equivalent of 1268 Olympic sized swimming pools! That’s a lot of lost water. This statistic may seem a bit random to include here but it’s important as we ask our next question: will we need more water in the UK?
The Government estimates that an extra 4 billion litres of water will be needed per day by 2050. You may notice this is only slightly higher than the loss through leakages, unfortunately there will always be leaks, so while this can be minimised it’s not the only solution.
Increased water demands are compounded by the fact that water companies are going to start extracting less water (1 billion litres per day) from natural supplies due to decreased rainfall. This will likely have been estimated using 143 litres per person per day estimate as opposed to the ‘hidden’ cost of 3000 – 5000 litres per day. It is not clear if this hidden cost is used by industries and agriculture when estimating water use.
So yes we need more water but fixing leaks will only do so much. Leaks cost a lot of money to fix and I doubt that the amount lost can be reduced completely. I also don’t know if this extra 4 billion takes into account future leaks, or leak fixing, because it might. In which case we may need even more water.
For you individually it will mean little. We are using more water each year so we need more water each year and we are extracting less water each year. At some point we do have to look at how we all use water and find ways to reduce it and I do not think individuals like you and me are at fault. However we do have a vital role to play in reducing water consumption and making it sustainable.
There are many ways to use less water in the home. Many water companies offer kits that make toilet flushing and showers more efficient. They also tend to offer advice on how to reduce water usage at home.
You can take a shower instead of a bath (unless you have a power shower which can use way more water depending on the brand). Reduce your time in the shower. If you half your average shower time you reduce your water consumption by half. Dermatologists recommend an average shower length of 2-5 minutes to look after your skin, so you’ll still be clean. You could look at things like washing your hair less frequently.
As the frequency of hand washing has increased at the moment, remember to turn taps off while washing your hands (wet hands, turn off tap, rub with soap, turn tap back on and wash off soap).
Only wash clothes when you have to and as a favourite adage of young children, if it’s yellow let it mellow! All these little things add up to make a big difference. BUT this only reduces your home water use.
Look at what you buy, where it comes from, and how far it travels. All of this can have a water usage cost (only switch if you are able, there are other things you can do if you can’t). And look at the energy costs, sometimes it’s not as simple as buying locally. Investigate the water usage of products and how much was needed to make it.
In the UK, do you really need to buy a bottle of water? Can you switch to a more efficient energy supplier, a greener energy supplier? These often use less water.
The biggest change you could possibly make (and it may be the hardest and least welcome change to some) is to switch to a diet consisting of less animal products (particularly beef). This is because to farm meat, not only do you need water for the animals, but also for the produce that feeds them whilst they grow. This change would also help with climate change for lots of reasons; less energy and land is needed for higher plant diets and there would be fewer farm animals producing greenhouse gases.
What if you’re already doing these things – or you can’t do them?
Make noise about water on social media to the companies. As consumers we have power to influence change, if it’s our priority it will be the priority of companies – and governments. For example, if you are angry about leaks, write to your MP about them. Or contact companies and ask them to become more efficient.
Regardless of what you do, try to consume less. It’s hard, really hard. Why choose to be less comfortable? Why choose something that’s harder to do or costs more? And the brutal answer is that if we don’t, one day we won’t have the choice, and it will be a lot tougher and harder than it would be to change now. Sometimes we don’t know where to start and that’s something the science community really needs to step up and address. Hopefully this gives you a starting point, something to think about and investigate.
What to read next? What is Life Cycle Analysis – interview with Rukayya Ibrahim Muazu.