Short Wave - Day Zero: When the wells run dry

Episode Date: March 23, 2026

In honor of World Water Day, Short Wave is exploring the ways water touches our lives. From increasing water shortages around the world, to how it’s affecting agriculture and aquifers. We’re starting with “day zero”: the day a city or place runs out of water. Cape Town, Mexico City, Chennai in India are just a few places that have come close to day zero events. Today, we talk to experts and hear from someone who lived in Cape Town during the crisis about why we’re overdue for rethinking our relationship to water. This is part of a whole series on the world's dwindling water supply. Check out the rest of the water series:Part 1: When the wells run dryPart 2: The world's groundwater problemPart 3: Freshwater's growing salt problemInterested in more science behind current events? Email us your question at [e-mail] to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave.See pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences.NPR Privacy Policy

You're listening to Shortwave from NPR. Hey, ShoreWavers, Regina Barber here with producer Rachel Carlson. Hi, hey Gina. Hey. So in honor of World Water Day, you and Burley, another producer here at Shortwave, are exploring the ways water touches our lives, from increasing water shortages around the world to how it's affecting agriculture and aquifers. And I've been looking specifically into that first part, shortages. For much of the world, normal is gone.

Earlier this year, the United States, nations declared the dawn of a new era, global water bankruptcy. Calling for a fundamental shift in how the global community understands our most vital resource water. Kave Medani is the director of the UN University's Institute for Water, Environment, and Health. And that clip is from a press conference in January. But Kave has been thinking about water for way longer than that. He grew up in Tehran with two parents who worked in the water industry. which of course is now experiencing more intense water crises because of the war.

Yeah, and he says he's been sounding the alarm about water in Tehran for years. I'm known back home for a person who was warning about these days. So this is happening. And then media contacts me and says, how do you feel? And what does he say? I wish I was wrong. It's miserable to feel and to know that your compatriots are suffering, you are going to suffer.

and the chaos, the fear, the stress. Even in my darkest projections, I was not thinking that Tehran would hit this day so early. And the longer this goes on, the closer Tehran could get to something called Day Zero when a city or a place runs out of water. Right, we've seen places come close to day zero, right? So Cape Town in South Africa, Mexico City, Chennai in India.

Tehran is not the first place that has experienced a situation like this and it won't be the last week. Today on the show, what happens when the taps run dry? How cities are coping and why experts say were overdue for rethinking our relationship to water. You're listening to Shortwave, the science podcast from NPR. Rachel, I think the first time I heard about Day Zero was in 2018 for Cape Town's water crisis. Yeah, Cape Town's a really big one. And I want to go back even a little further. to 2017, Cape Town was experiencing a huge drought. Some water restrictions were in place,

and people were starting to think about how to conserve water a little bit more. You don't have to shower every day. We shower every other day, every three days, make their shower shorter. That's Aaron Baker. She's a freelance journalist who lived in Cape Town from 2014 to 2021. Well, she was there when all of this was going down. Yeah, and she remembers it all super vividly. Aaron says in the midst of the drought, a lot of people were holding out hope, kind of like, well, the rains are going to come, the reservoirs will fill up. But they did it. And the rains?

They kept not coming. On February 1st, 2018, every resident in Cape Town was limited to a maximum of 50 liters or about 13 gallons of water per person per day. How much is that? Like, what can you do with 13 gallons? Not a ton. So the EPA says the average person in the U.S. uses 82, gallons of water per day. So 13 gallons. That's one 90-second shower. Two liters of drinking water. If you have a dog, you always have to count in your dog. That's one sink worth of hand-washed dishes or laundry. One or the other, not both. One cooked meal, two washings of your hands,

two brushing of your teeth, and one flush of the toilet. So Erin is doing the math. She's making all of these calculations and trying to figure out, like, how many times do I really need to flush the toilet? Even her daughter, who's seven or eight at the time, is aware of it too. Like, no, mommy, we can't, I can't shower. I can't take a bath today because of the water issues. Wow, yeah. So, like, even kids are taking personal responsibility. Yeah, I mean, Aaron told me that the kids were learning about it in school and just all of these questions were circulating. Do you really want to use your precious water supply, even if it's recycled, water. Do you really want to use it for the toilet?

I want to break this down, though. How does a city like Cape Town get to this point? When it comes to Day Zero, the exact circumstances of every city are different, but there are a few things that they tend to have in common. Among them, leaky infrastructure, mismanagement of water, depleting aquifers, and more people living in cities, meaning more demand for water in concentrated regions. And climate change? And climate change, yeah. I talked to Felipe Omenga. He's a professor of geography at the University of Bergamo in Italy. And he referred to climate change as... An enormous sort of bonus card.

Really not the bonus card you want when your deck already includes all those other things. Yeah, and I know we're going to get into like one of those factors, aquifers. That's tomorrow's episode. But Rachel, maybe for today, can we just zoom into that bad infrastructure part? Yeah, I talked about this with Manuel Perlow. he's an economist in Mexico City where there's been an ongoing water crisis for years.

30 to 35% of the available water gets lost in leaks in the public distribution system, yes. Wait, like leaky pipes? Yeah, and that's a global problem. In the U.S., the EPA estimates

around 1 trillion gallons of water each year are wasted, just from household leaks. Wow. There's a big engineering problem. And a financial one, right? Yeah, and then on top of that in Mexico City. Another 10% gets stolen from the system.

What does he mean by stolen? When water is scarce, it's also profitable. So cartels or groups will steal water from pipes and then sell them for a lot of money. So you have around 50% of the water lost on its way to the consumers. Other estimates say, it's around 40%, but either way, the distribution of who is actually getting water usually isn't equal. Large parts of the population do not get water at all in Mexico City. They are not attached, connected with the public water system.

They've never been connected. Those are the people that live in a day zero situation. always. Okay. So for some people, Day Zero has been here for years already. Yeah, exactly. Lower income groups spent a lot of their family income in water. Sometimes 20% of their whole income. They are the ones who suffer the most, but the problem affects the whole city. There's no question about that. That's something Aaron brought up too, especially for a lot of less wealthy people in Cape Town and the surrounding areas. they were already experiencing water scarcity for years before the drought and before water restrictions went into place. So the shanty towns and the townships, they were not wasting water because these were the people who had to fill buckets to take the water to their house.

So obviously they understand the value of water because it's measured in backache. There was one study published in the journal Nature a couple years ago, and it looked at all of this after the fact. They used a model to estimate that the wealthiest households in Cape Town were using over 50 times more water than the lowest income houses they looked at. But everyone had to cut down on their water use or risk being fined, even people who weren't using very much to begin with. Wow. So even the restrictions weren't necessarily equitable either. Exactly. So what did end up happening in Cape Town in 2018? Cape Town city officials knew they were in big trouble when it came to water.

So they'd started building temporary desalination plants as an emergency measure to have more fresh water for people to use for drinking. But what actually let the city avoid day zero... What happened was that it started to rain. Wow. Philippo called it a mezzianic rain. And I mentioned that to Aaron, and she agreed. Oh, it felt so good. Yeah, it was totally biblical.

I mean, we were all... I mean, it's not like we were dancing in the streets. It was cold. But, I mean, you do have this sense of religious. Oh, but that's not something you can count on in the future. Right, especially not with climate change. They were super lucky. And Aaron says a few years later during COVID, all she could think about was how many times

every single day people were washing their hands. And I was just thinking, if we had had the water crisis combined with COVID and the sanitary measures that you needed, that would have been a freaking disaster. So you can kind of hear, Gina. Aaron's mindset around water has flipped since 2017. And that's the kind of thing Kave says needs to happen for all of us, because people often assume water is abundant. Or maybe at worst, they say there's a crisis. How can something be a crisis for almost 15 years?

Maybe this is a wrong terminology for a chronic problem. At this point, Kavei says maybe we're past the point of crisis. A crisis is a shock. It's a temporary deviation from a normal that you're used to. But if the crisis is there forever, if it becomes chronic, it's part of the system. That's an essential element of the system that you need to face. Okay, so he's saying the situation isn't temporary. So we need to completely change our approach to water.

Exactly. And my conversations with people like Kave who study water and people like Aaron who understand how precious water is, all came down to one thing. We treat water like it's free, but we can't. Whenever you have touched the tap, you have had water, and all of a sudden you have to get used to a new sort of life. Even now, if I hear a dripping faucet, I have a visceral reaction to, like, this is precious stuff. We can't, we can't let that go. Rachel, thank you so much for bringing us this report. Yeah, thank you, Gina. If you liked this episode, tune in tomorrow.

We've got another water story for you, this time on aquifers, the water beneath your feet. And if you have a second, could you share this episode with a friend? It helps us grow, and it helps us continue to make episodes like this one. This episode was produced by Burley McCoy and edited by a showrunner Rebecca Ramirez. It was fact-checked by Aru Nyer. The audio engineer was Jimmy Keeley. I'm Regina Barber. Thank you for listening to Shortwave from NPR.