Instant Genius - Global heatwave: Could our taps soon run dry?

Episode Date: July 20, 2023

Last month saw the hottest June on record – and, while July has seen heavy downpours in the UK, much of Europe and the US experienced life-threatening heatwaves. As things heat up, aquifers shrivel – and London’s 90-day supply of water means the city is never far from its taps running dry. That’s Day Zero: a benchmark that several cities around the world have come alarmingly close to – or, in some cases, even reached – in the last decade. But what happens when that day comes? In today’s episode we speak to Professor Priti Parikh, infrastructure engineer at University College London, about the looming threat of Day Zero and how household tricks all the way national innovations can offer promising solutions. Learn more about your ad choices. Visit podcastchoices.com/adchoices

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Last month saw the hottest June on record, the arrival of increasingly normal hosepipe bands, and water infrastructure targeted in the Russia-Ukraine war. And while July has seen heavy downpours in the UK, much of Europe and the US, experienced life-threatening heat waves. As things heat up, aquifers shrivel, and London's 90-day supply of water means the city is never far from having its taps run dry. That's day zero, a benchmark that several cities around the world have come alarmingly close to, or in some cases already reached, in the last decade.

But what happens when that day comes? In today's episode, I speak to Professor Pretty Parique, who specialises in infrastructure engineering and international development at University College London. Pretty tells us about the looming threat of day zero and how household tricks all the way to national innovations can offer promising solutions. So Pretty, please could you tell us what day zero is? Sure. So day zero is the countdown to when a city or location would run out of water. And this phrase was coined initially in South Africa in Cape Town where there was a water crisis in 2018 and the city which had four million people were at a risk of being left without water and this led to a serious kind of campaign and

restrictions on water use so in January 2018 for example the city of Cape Town they declared water restrictions of using 87 liters per person per day decreasing it to 50 liters per person per day and the actual day zero, the day that the city would run out of water, was estimated to kick in either April or May. And there were complicated calculations around when this day would occur because the city is dependent on water supply from six dams. But luckily, it rained and day zero did not happen. But it is quite striking that we had a city of four million residents

who were left at the mercy of rains. So what would we actually see if, day zero were to come upon us? So I can give you the example of Chennai, which came closer to day city. So Chennai is the sixth largest city in India with about between 6 and 10 million people in the city. And as they came closer to day zero, there were kind of restrictions on water supply to houses, which meant that people had to take buckets and queue up for water collection.

they had to purchase water from private vendors at very high cost. But I think a big impact was on local businesses and on hospitals because people forget that to provide vital healthcare services, you need access to water. And this meant that a lot of vital operations in the city started to be impacted. Once again, the city was safe by rain, but it was a very serious situation affecting kind of mental health and mental health, being, kind of economics of the city, but also the social fabric of the city. So what does it take for

this to happen? How many years of drought or infrastructure damages can we take before we reach day zero? I mean, as human beings, we have over-exploited environmental resources on our planet. So in places where we rely on groundwater, we keep on pumping and extracting groundwater. And this process happens over the period of years. So if we go back to Chennai, for example, they had about thousand small lakes, wetlands, water bodies, which provided water in the last 30 years or so with urbanization that has reduced to 200.

So, I mean, this is a process which takes a decade, two decades in the making, but we see an increase due to climate change because now what is happening is we have drier summers, wetter winters, and that is not helping, in building up reserves for water. So how close is the UK to day zero? And have we come close to it in the past?

So we've had droughts over the last few summers. And for those who may remember, for example, last year we had a host pipe band for gardens. And we started talking about restrictions on car washing and how we use water in the garden. It's not hit drinking water yet. But if you look at our Environment Agency's National framework for water resources. It has identified water scarcity crisis as a huge risk. It has identified

that we need to act now. So we need to boost our water resources. We need to reduce leakage. We need to reduce demand. And we need this action plan to build resilience in a water supply. Otherwise, we do run a risk of running out of water in England. And I know people will be surprised by this because it does rain a lot in our country. But the amount of rain is actually, not enough. And I think we are all noticing that here our summers are getting drier. As far as I'm aware, London only has 90 days of water supply at any one time. So the infrastructure that we're running on beyond not having enough water is also quite vulnerable to running out, really. So how can we prevent, or at least delay day zero? So there are a few things we can do.

One is leakages. I mean, people talk about leakages as the solution. Leakages or addressing leakages in the water infrastructure system is part of the solution. And in countries, the range of leakages varies. So in UK, it's about 20%. So that would lead to some form of saving. Then we have water meters, which will enable households to look at how much water they consume, to see if they can change their behavior. But behavior change actually is a big piece in this in how we look at water, how we consume water. And it's not just the actual water that we drink

or we use for showers or for washing clothes. We have a high water footprint, which is actual and virtual water consumption. Let me give you an example. Do you know how much water we need to produce a kilogram of beef? It's 15,000 liters. How much do we need for a pint of beer?

Between 90 and 150 liters. and a cup of coffee is 130 litres. So I think a big kind of piece of the puzzle is for ourselves to look at our consumption patterns, our behaviours, to see how much water are we actually consuming for us to understand what our true water footprint is. Because in a city at the scale of London, every little bit will matter.

So how does the UK's water footprint compare to other countries? Sure. So UK, on average, it's about between 120, 150 litres a day, which is high. So if we benchmark ourselves against water scarce regions like Jordan, that's double. Jordan is down to 50, 60, 70, depending on seasons. But we are not the highest. US, the water consumption per person is double. And that is huge. And that needs to really change. because this is not a sustainable model. The problem is that on this planet, it feels like we have a lot of water, but the amount or proportion of water that we can really use easily, it's about 1%. And when you're talking before about how much the water footprint of all of those different foodstuffs and items and activities that we consume or we do in our day-to-day lives, where does waste come into that? Does that have a huge water footprint too? How does it compare to consumers? consumption. The agricultural sector requires water as well. So if we do not have water, it poses a food security crisis. So it means that any form of food wastage has to be avoided. Food wastage

would be of two types. One would be how we store and distribute food, which is quite a big challenge in some parts of the world, like India, or it could be in our own behaviours in making sure there's no wastage. But from the agricultural water use perspective, it's a absolute no-no food wastage. But also, as I've highlighted some of the stats earlier, if we put in 15,000 litres of water to freeze a kilogram of beef, if there's any wastage, there's a huge amount of water which is lost. And also, with that water loss, if we are contaminating water for a productive use, it means that we have to invest resources, energy, into treating the water. Are we going to have to give up our extra showers, our carcule,

cleaning, our watering of kind of ornamental plants in our garden, the privileged humans have to just accept are going to be a thing of the past? With climate change, I'm concerned that yes, we will have to revisit, reconsider our lifestyle choices, whether it's how car washing, watering gardens, or consumption. Even when I say consumption, it's even things like food, clothes, because every activity takes of water. It could be laundry. How frequently do we need to wash our clothes?

Because previously, we did not have this culture of using washers and washing clothes at this frequency. There's an expectation now that we need to change clothes three or four times a day, and we need to have frequent washing. So we need to look inwards within our lifestyle choices to make sure that our practices are sustainable, that we are doing whatever we can to replenish local water resources, because this needs to be a joint effort with water companies, with government, with ourselves, to safeguard future water supply. So how does our personal consumption, our water footprint,

compare to some of the bigger activities? So I think when we look at water footprint, we do need to look at it holistically because, for example, we use laptops and there is water consumption, in using laptops. So the whole process of industrialization, transportation, all those functions need water. So there is a fundamental question to be asked in our cities around the type of big mega projects and infrastructure we have, whether that is the right form of infrastructure. Unfortunately, with high densities, the types of solutions we come up would be around concentrating efforts on networked infrastructure. But there are interesting kind of initiatives

and examples of water conservation in rural settings. For example, rainwater harvesting is something that comes to mind. Because with rainwater harvesting, if it's done at neighbourhood or community scale, it has huge potential to capture rainwater, which could be then used to support depletion of groundwater, could be used for various water needs in households. So I think for me, rainwater harvesting at scale also holds promise along with nature-based solutions. So is this a problem that is just restricted to some parts of the world, or is it a bit wider than that? So people believe that this is a problem of the global south or what we call low-middle-income countries.

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One would be rivers, reservoirs, from which there would be piped networks. So there would be infrastructure which transports water over long distances to be then distributed to households. And this comes at the cost because you have the infrastructure, the pipes, but then the water might need to be pumped to meet the required level of pressure. Because if you open the tap, you want a reasonable amount of water to come out. So that's one source. And the second source is water under the ground, which we don't see a lot, but that's a key source of water for us. And that could be through wells. And that is a source that has been overutilized. I grew up in India, for example, where the water tables in my hometown, which is the fifth largest city in India, was down to about 250 feet below ground.

And what that means is in extracting that water source, you would use huge amounts of electricity. to be able to extract that water source. And that poses an interesting problem of equity, because it means that those who can afford to invest in electricity get more water. And we see this playing out in parts of India. We've seen this playing out in Jordan, where it leads to lack of equity. Could you tell us a bit about how groundwater is structured? I was learning about how interesting it is that it's like a sponge and it kind of fills and drains a bit like that. So could you unpack that a little bit for us? Sure. I mean, nature is amazing. It feels like if you think about nature, everything has been taught through and there is a method behind the madness. There is kind of

a term commonly used called sponge cities to imply that our cities are like sponges, which, so underground, what happens is water is absorbed between different layers of soil. And water accumulates in what we call is aquifers, and hence there is potential to extract and use the water from aquifers. And under normal circumstances, what happens is the water gets recharge through processes like rainfall. But what has happened is with over-utilization and extraction, the recharge process does not happen anymore. So we go deeper and deeper into ground to extract water. So the whole mechanism of cities being sponges no longer works. And that's why nature-based solutions are kind of the key way forward to address some of those gaps. And what do I mean by nature-based

solutions, finding ways of using kind of the lay of the land to capture water again. So one of the solutions, which is most commonly used, is sustainable urban drainage system. Suts. And what that is, it's pretty much opening up channels and open drains to collect rainfall, to collect water, to allow it to percolate into the ground and for groundwater to be recharged. In Rajasthan, in India, there is a very interesting initiative around rainwater harvesting where there would be underground tanks built either out of stone or bricks or concrete, where rainwater and surface around from roofs is collected, and then it can be used for irrigation purposes,

it can be used for fulfilling other water needs. Another interesting intervention, I mean, which Israel is really leading the pathway on, is what we call drip irrigation, where you get smarter and better about how we use water for agriculture. So with that, you would have a pipe with holes and you would feed water through it carefully so that it waters the roots of the plant to reduce wastage.

One of the challenges with this technology, though, is it does not quite be challenged. charge the ground around it. So that's not a perfect solution in terms of improving water resources. It's a good solution for agriculture. That's really fascinating and great that there are these positive solutions that we can address or use to address the water scarcity crisis. Sadly, I'm going to take a negative turn because as far as I understand it, some of this damage is irreversible. The example's being quoted of Mexico City kind of sinking under its own weight because the empty groundwater reserves, instead of being that full sponge, go a bit more like a kind of crumbly dry sponge and brittle.

Could you talk a bit more about some of these impacts that we might already be seeing of water scarcity that goes beyond human and environmental consumption, but more structural? Yes, absolutely. I mean, Mexico City is an example, San Paulo in Brazil as well. So there are parts of the world where as a due to a combination of misuse of land, I'm just going to say misuse of land. I think that's the most appropriate way of putting it, climate change, pollution. We have destroyed watersheds permanently. Traditionally, the way our cities work is we would have natural drainage parts. The cities would be able to naturally kind of revive itself, but now we've built over those water systems.

So some of the damage we've done is reversible. And what that is leading to is parts of world, I mean, I gave the example of Jordan, for example, where there is a serious water crisis, further enhanced by the refugee crisis as well. So we have more more people now needing water in the water scarce region and where some of the reservoirs that there are beyond repair. And desalination, for example, is seen as a solution to the problem. But desalination, the brine or the solution coming out of desalination is causing havoc to our environment because it's leading to very simply put deposits of salt in our oceans. And that is leading to damage to marine ecosystems. Because once you have layers of salt building up at the bottom of our oceans,

it starts affecting kind of the ecosystem, it starts affecting kind of fish, for example. and that goes into the food chain. So what we're doing here is we are causing havoc to our ecosystems as a result of high consumption, our behaviors, and further thing pollution. We are polluting the resources that we desperately need. And I think one key message is that with water resources, it's scarce, it's a precious resource,

and we keep on polluting it with human activities, which means we have to then spend more and more to treat the limited resources we have. You have mentioned a couple of times about climate change already so far. And I just was hoping to talk a bit more about some of those impacts of climate change. So droughts, obviously, and the heat and evaporation of water, but also possibly the melting of polar ice caps. All of this plays a part.

We live in an ecosystem where if there is a problem with a part of the system, it has a knock-on impact on other elements. So the melting of glaciers means it starts impacting kind of water resources. So it means there could be flooding, for example, that starts impacting on agriculture, it starts impacting on kind of natural resources. One thing that people forget is as a planet, as countries we are interconnected, climate change is a joint challenge. And within that water resources and the water crisis,

It's very much center stage of climate crisis. Because, for example, flooding has its own challenges. Because with flooding, which is one of the byproducts of our glaciers melting, it leads to contamination of our environment. It leads to spread of disease. But in then other parts of the world, if there is less rainfall, so if we have droughts, for example, that leads to kind of health challenges and disease as well. For example, in sub-Saharan Africa, there are communities who are migrating from villages to cities in search of water,

and that's putting more pressure on cities, which are already transporting water from miles and miles away. So what happens as a result of climate change is it impacts migration. Then we start getting cities which are highly water stress or water scarce. So that's a key challenge. But if we talk about London, for example, or our context here, we have what we call combined sewer overflows. And what that means is during periods of heavy rainfall, some of the rainwater is allowed to go into our sewers, which in turn would then be discharged with treatment into rivers. But as a result of heavy rainfall, what is happening now is there has been incidence of kind of sewage discharge in rivers. to our rivers and the frequency of this is increasing. And this is quite serious because now

this starts polluting the limited water resource we have. There's going to be an investment needed into fixing this problem, which is thinking about kind of systems for capturing rain water, which is also tricky because it does not rain throughout the year. So for example, the problems we have with rainwater management is that if we take a country like India, rainfall hits us in three months. Now, if we design infrastructure for that period, it's huge infrastructure, it's expensive, and it has implication on how our cities are formed in shape. Now, migration is really a serious issue, and people will be shocked here that every week we're building a city of the size of Paris. And that's not fully down to climate change,

but it's an indication of how serious the migratory problem is. But climate change, has a huge contribution to this. In terms of creating climate refugees, in terms of impacting agriculture, so it's no longer feasible for farmers to be fully engaged in farming activity. Because the one thing that farmers need is access to water at the right point in the year.

And as our rainfall patterns get erratic, it is impacting on their livelihoods, which means they go out to cities in search for work to make sure that they can educate their children, make sure they get decent health care, all the facilities that they deserve. Now, the debates and discussions say in UK and overseas are different because a large part of the food production happens overseas. Like in London, I know that in terms of food reserves,

we would probably run out of food in 20 days, or we have 20 days' worth of supply of food. So a large part of food production actually takes place overseas, where there are pressures on water resources. It's amazing when we talk about London having 90 days of water and 20 days of food. You just realize just how vulnerable some of these systems are, don't you? But that comes back to consumption because when we account for our consumption, we don't count the fact that we importing food from overseas.

It's been grown somewhere. So we've actually consumed water from a country which is struggling with water resources. So coming back to your question of food shortage, that's why it's important that we're very considered on how we store food, how we use and consume food, because we're actually taking water away from another country, if you think about it ethically. And that is a huge ethical dilemma. Definitely. That's a really important point. And you've spoken a lot there about migration and those kind of geopolitical impacts.

So my next question is it kind of turns back to that. The monopolization of water is the stuff of dystopias. and in fact, I think one of the more recent James Bond films kind of centered around this idea. So could water become increasingly valuable, even invaluable as a resource, a bit like oil in the future? Yes, I mean, people talk about oil wars, but water is the one to watch for, because we cannot live without water. It's as simple as that. So water wars is already happening, whether it's past of Middle East, whether it's sharing arrangements of, water in South Asia, water walls are already happening. I mean, when you have kind of water resources which is shared between two countries, it's extremely challenging because then you need to have

arrangements of how to manage upstream and downstream water, make sure there is supply of water available to residents. And I keep on coming back to Jordan in part because I actually have a research project there. But one of the challenges with Jordan is that they have limitations of how much water is available to them. And the problem is going to get worse. Then it means they'll have to pay more and more to acquire water. But there are politics. I mean, water is not free from politics. So the geopolitics do have a role to play around water resources. There's also issues around justice. So even in the same city, you will find that people from high and middle income groups will be able to afford water. People from lower income groups will not afford water.

All they pay, even if they pay the same amount, it's a larger proportion of their salary. So if they pay 10, 20% of their income on water, there's a justice issue to this as well. South Africa, Australia, India, places that have been dealing with water scarcity for a long time. What are some of the exciting innovations and what can we learn from these places? Sure. So one thing that is not spoken about lot is landscaping. So planting trees, we know, is good for the environment, it's good for emissions. But what happens with landscaping plantation is that when there is heavy rains, it stops or reduces or slows down the flow of,

brain. And what that means is it then enables more water to be absorbed in the ground along the route. So rather than water being washed off into the river and having dry areas in between with the right type of landscaping and plantation, that could start kind of reducing challenges on groundwater. At household level, there has been kind of interesting kits and innovation around can we take water from washing machines, can we take water that we, we use what is called gray water. The water that we use for washing hands, for example, can we take that water and reuse it? So at household level, I mean, there are those tweaks and innovations.

Of course, we talk a lot about showers and how can we restrict flowing showers, how can we put time us on showers. So there are innovations at household level, but also at scale, I would say. And, I mean, one interesting fact is that the water that we drink has been treated and reused multiple times. So in a way, when people pee, that water is collected, that's treated, and then that is discharged into the river.

And in London, for example, the water we drink has been treated at least seven times, which is an innovation, but requires a campaign on acceptance as well, understanding that if the water is of right quality, we can take pee and we can treat pee to make it a powerful tool. You've been listening to

infrastructure engineer Professor Pretty-Pourique, talking about water shortages and day zero. Thank you for listening to this episode of Instant Genius, brought to you by the team behind BBC Science Focus magazine. The latest issue of Science Focus is on sale now in supermarkets and newsagents, or through your favourite app store. You can also visit us online at sciencefocus.com. This podcast is sponsored by name, audio and focal. The texture and emotional depth of music can be lost through digital sources or poor signal. Name Audio believes you can have digital precision with analog warmth. Alongside French acoustic specialist vocal,

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