In February 2025, scientists at the University of Chicago moved the Doomsday Clock to 89 seconds to midnight. The clock is a metaphor for humanity's risk of extinction and this is the closest it has ever been to 'boom-time'.
But given the state of the world, who could blame the scientists for their horror-logical tinkering?
Climate scientists warn that we’re behind targets to prevent catastrophic climate change. Artificial intelligence continues its march despite the omens of multiple experts and Hollywood movies. Even bird flu is attempting a comeback.
So it’s perhaps no great surprise that an increasing number of people aren’t hanging around to find out which aforementioned apocalypse strikes first.
Concerned citizens and governments alike are investing in underground shelters, designed to sustain life in the event of a doomsday scenario.
Notable members of this underground movement include Facebook founder Mark Zuckerberg, who is reportedly building a vast shelter, with its own food and energy supplies, in a compound in Hawaii. Former Microsoft CEO Bill Gates is also reported to have huge shelters under his homes, in California and Washington.
But it’s not just the super-rich who are bunker-curious. Nation states have also explored the idea.
At the end of 2024, Switzerland announced plans to revamp its vast network of 360,000 underground shelters – enough to house more than 9 million people. (In Switzerland, every citizen has a right to underground shelter thanks to a law passed in 1963.)
Meanwhile, in Finland, the city of Helsinki is often hailed as the gold standard of underground civil defence planning, with huge spaces built not only for ‘just-in-case’ scenarios, but integrated into modern life with swimming pools and restaurants.
The UK has a number of Cold War-era bunkers, but experts agree that most of them are no longer fit for purpose. With no sign that the government is building new shelters, some people are working with specialist firms to construct their own liveable underground spaces.
“Most of my business was panic rooms, safe rooms, security doors and windows to make a secure area inside the residence in case of home invasion. Now, I’d say it’s 50/50 between that and underground shelters,” says Paul Weldon, who runs The Panic Room Company.
He says the shift started with the onset of the Ukraine war, and that he now builds custom bunkers in the UK and abroad. But it’s not just the ultra-wealthy who are doing it.
“It’s come further down the food chain,” Weldon says. “For example, we’re getting enquiries from people who have already got a basement and they want to make it secure. Then you’re talking £100,000 as opposed to half a million minimum for a bespoke underground bunker.”
Weldon believes that a full-scale nuclear winter isn’t the most realistic risk. Instead, he says most shelters are built as a shorter-term getaway in the event of floods, serious civil unrest or even a dirty bomb.
So, should you start digging out the garden? If so, how should you design your shelter? What should you stockpile? And how do you supply it with clean air, water and energy?
Fear not – or maybe a lot, if that’s where your head’s at – because we’re digging deep into the subject, offering triple-reinforced tips on how to build your very own underground bunker.
Engineering
The average, ‘garden-variety’ bomb shelter isn’t designed to withstand a direct hit. You’d have to be extremely unlucky for a warhead to land directly on top of you.
“The idea of putting them underground is in case there’s a blast a few miles away, as the energy released travels horizontally and will pass over the bunker,” says Weldon.
For a family of five, he recommends a shelter that’s around 8 x 4m (26 x 13ft). This would allow you to survive in some comfort with at least some individual privacy.
The majority of shelters are made from concrete. “You can use lead, but it’s very expensive to do,” Weldon says.
“If you were building just an underground car park, for example, it’s no different to that. The thicker the concrete, the greater the protection from blasts and radiation. For a NATO-grade shelter, it’s probably 2–3m (6–9ft) concrete in width and a couple of metres of concrete on the top.”
Scientists have run the numbers on what you would need for full-scale nuclear fallout.
“In a worst-case scenario, the level of protection offered by radiation shielding materials, such as high-density concrete, is determined by their ability to attenuate both neutron and gamma radiation effectively,” says Prof Patrick Tang at the University of Newcastle, Australia.
In 2024, Tang co-authored a review of radiation-shielding concrete. He recommends heavy concrete with a density greater than 3,200kg/m³ (200lb/ft³). This offers a ‘dose transmission factor’ that prevents radiation from fission bombs penetrating the shelter.
“This level of thickness ensures that the dose behind the shield remains at or below 0.0001 sieverts [units of harmful radiation], which is considered safe for human exposure,” he says.
You’ll also want some blast doors. These can protect you from explosions and flooding.
“The door can be stepped into the concrete wall and you then pour concrete into the door itself,” says Weldon. “Alternatively, you can use steel. The style we use is about 20mm (almost 1in) thick with a steel film that, again, is set into the concrete. That’s the initial [door], but we double up.”
It’s the end of the world, after all – you can’t be too careful.
Read more:
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Services
Clean air. Electricity. Ideally, Wi-Fi. These are some of the creature comforts we would put on our wishlist for a doomsday shelter. Most of them are fairly straightforward to install.
Power can come from a mains link-up, backup generator or a self-sufficient energy source, such as surface-level solar panels.
If you want to speak to the outside world, Weldon says that internet and satellite phones are also fairly standard, with external aerials wired to the bunker. “More and more we also fit with Starlink,” he says, referring to the massive satellite constellation that provides internet access almost anywhere in the world.
Ensuring fresh air in the sealed environment is also critical, says Antonia Cornaro of the International Tunnelling and Underground Space Association, based in Switzerland. “Many shelters use high-efficiency particulate air (HEPA) filters or overpressure systems to keep out contaminants.”
HEPA filters are designed to keep out 99 per cent of particulate matter, while overpressure systems are standard for any structure designed to protect against chemical, biological, radiological and nuclear threats.
It creates a safe area where the air pressure inside the bunker is higher than outside, stopping contaminated air from entering.
Food
In February 2025, the UK's National Preparedness Commission published a report called 'Just In Case', looking at the country's food resilience in case of emergencies. It's a sobering read.
It concludes that "the UK now lacks a coherent food security and resilience strategy fit for... 21st-century geopolitics."
The report’s author, Prof Timothy Lang, studied other countries’ preparedness for so-called food shocks. “Switzerland stores three months of major commodities and a year ago they passed a regulation saying they’re going to raise it to 12 months,” he says.
“Germany gives very detailed official advice, even for vegetarians and non-vegetarians and so on.”
German authorities recommend that citizens stockpile 10 days’ worth of food per person, based on 2,200 calories per day and offer detailed nutritional breakdowns. These include 3kg (6.5lbs) of grain products, bread and potatoes; 4kg (almost 9lbs) of vegetables; 2.5kg (5.5lbs) of fruit; and 1.2kg (2.5lbs) of meat, fish and eggs.
For something more extreme, the Mormon Church advises its members to have a three-month stockpile.
In the UK, there’s no such advice. So, what should you have in your store cupboard or bunker? The obvious examples are tinned goods – low-acid meat and vegetables, which can last five years or more.
“We have tins with a shelf life of 25 years,” says Leigh Price, owner of survival and emergency supplies store The Bugout. “But realistically, if you store them correctly, they’ll never go off.”
Price also sells packs of freeze-dried foods, similar to the pouches stored on the International Space Station. “It’s pre-cooked food – chilli con carne, for example – and it’s freeze-dried to take out all the moisture.” That way it can be stored long-term and heated safely.
For Price, who grew up in mid-Wales, storing food is natural.
“I remember in 1982 when we had a blizzard, we were cut off for four days, but most people had a good pantry full of food and tins. Speak to farmers – they always need to make sure there’s plenty of food in the house. It’s just people have lost that way of living because [shopping] is so convenient now.”
In 2023, a pair of supply chain researchers based at the University of Bradford argued that stockpiling a reasonable amount of food is something we should all start doing again. “Prepping – thinking ahead and being proactive – is the opposite of panic buying,” they said.
Water
Humans can live for around 30 days without food, but only three without water, so any underground shelter requires some liquid thinking. In the bunkers he builds, Weldon keeps things simple.
“We use the big water dispensers you see in offices for clean water, or larger containers that can be filled if it looks as though something’s going to happen,” he says. “In one installation, we had a very simple steel wash basin with two tanks underneath, one for fresh water and one for waste, all operated with a foot pump.”
Drainage becomes important if you’re underground for any length of time, so Weldon builds that into his designs, along with toilets that have special valves. For larger-scale shelters or underground civil spaces, location is key.
“If you can access groundwater or an aquifer, then you’re able to bring in fresh water and discharge waste at scale,” says Antonia. “And wells, of course, are possible.”
But assuming you don’t have a well in the garden, how much clean water should you stockpile? Fortunately, the World Health Organization has done the sums for us…
| Water use | Required volume (litres per day) |
| Drinking | 2.5-3 LPD |
| Hygiene | 2-6 LPD |
| Cooking | 3-6 LPD |
What's in your go-bag?
Everyone from the Red Cross to the British government recommends that you keep an emergency kit ready for just-in-case scenarios, such as floods, fires and power cuts. Your go-bag should contain items that’ll keep you safe based on the likely risks in your area, says Price.
“It depends if you’re in, say, a flood zone – what are the essentials you’d need? You’re not talking about 9mm pistols and all that rubbish. It’s just practical stuff. If you’ve got kids, you might want to take some colouring boxes and playing cards in case you have to vacate your house and go to the local sports hall, maybe overnight.
“Preppers get a bit of a reputation that they’re all waiting for the end of the world. But it’s not that; it’s just being proactive and making sure you and your family are safe and as comfortable as possible if something happens.”
Here’s a starter kit, based on the combined advice of multiple government and charity sources:
- Bottled water (three gallons per person, ideally)
- Tinned meat, fruit and vegetables
- Other non-perishable meals (such as freeze-dried or dehydrated meals)
- Warm and waterproof clothing
- First aid kit and any regular medication
- Battery or wind-up torch
- Battery or wind-up radio
- Solar-powered batteries
- Multitool
- Hand sanitiser and/or wet wipes
- Baby supplies (such as nappies, formula) if required
- Local maps
- Lists of vital phone numbers and addresses
Is our future underground?
The underground isn't just for the 'End of Days'. Some civic planners and environmentalists believe the subsurface is an underused resource. So, what could we do down there?
Agriculture
Underground farming involves growing crops beneath Earth’s surface in controlled environments, such as tunnels, basements and abandoned mines. It relies on artificial lighting, hydroponics and climate control to create optimal growing conditions without relying on sunlight or weather.
Advocates, including the operators of a farm in the London Underground, argue that the method conserves water, reduces the need for pesticides and allows year-round production, while increasing food security in densely populated areas.
Earthscrapers
Imagine an inverted skyscraper that extends for storeys under your feet instead of over your head.
Developers claim that building earthscrapers will save on steel costs, as well as on heating and cooling systems. Proposed examples include the earthquake-proof complex Underground Science City, planning to house 4,500 researchers in Singapore.
In 2018, the InterContinental Shanghai Wonderland hotel was built into the side of an abandoned quarry outside Shanghai.
Hyperloop
One of Elon Musk’s many projects, Hyperloop is said to be a high-speed, low-carbon underground transport system where passenger pods travel through low-pressure tubes that reduce air resistance and allow speeds of over 1,120km/h (700mph).
The idea is that by using magnetic levitation and electric propulsion, it will reduce travel times between major cities. But the project still has many technical challenges to overcome before it can become a reality.
About our experts
Paul Weldon runs The Panic Room Company, based in the UK. The Panic Room Company specialises in fitting safety rooms, doors, panic rooms and now safety bunkers to people's homes and other buildings.
Prof Patrick Tang is a professor of architecture and construction management at the University of Newcastle, in Australia. He edited the book Green Concrete for a Better Sustainable Environment and has been published in scientific journals such as Applied Thermal Engineering and Toxics.
Antonia Cornaro is the co-chair of the International Tunnelling and Underground Space Association, based in Switzerland. She has co-authored the book Underground Spaces Unveiled: Planning and Creating the Cities of the Future. She is also published in the likes of Tunnelling and Underground Space Technology.
Prof Timothy Lang is emeritus professor of food policy at City St. George's University of London, in the UK. He has been published in many books, including Feeding Britain: Our Food Problems and How to Fix Them and Food Wars: The Global Battle for Mouths, Minds and Markets. He is also published in scientific journals such as Journal of British Studies and Sustainability.
Leigh Price is the owner of survival and emergency supplies store The Bugout.
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