Why Three Days Is the Right Place to Start

Most UK households are around nine meals away from an empty cupboard. That is not a criticism of anyone's shopping habits — it is simply what happens when we shop little and often and rely on a fridge that needs electricity. A three-day supply is the sweet spot for British homes: long enough to cover a prolonged power cut, a burst water main, a flooded road that keeps you indoors, or the kind of snow that stops deliveries for a few days, but small enough to fit in a cupboard without turning your kitchen into a bunker.

Three days is also the figure used in most official emergency guidance, which makes it a sensible target rather than an arbitrary one. Aim for roughly 2,000 calories per adult per day, so around 6,000 calories each across the three days. Children need less, teenagers and anyone doing physical work need more. Add pets, formula-fed babies, and anyone with a medical or dietary requirement to the list before you buy anything.

The good news: you probably already own half of it. The other half is a single, calm trip to the supermarket.

Build It From Food You Actually Eat

The single biggest mistake people make is buying a box of unfamiliar survival food that nobody in the family will touch. If the power is off, the weather is grim and everyone is already stressed, that is not the moment to introduce a new flavour. Store the tinned chilli your lot devour on a Tuesday. Store the custard, the oatcakes, the peanut butter, the instant noodles, the dried mango.

Work through your normal weekly shop and ask a simple question of each item: could this sit in a cupboard for six months and still be welcome on a cold evening? If yes, buy one extra and put it aside.

Good candidates for a British three-day box:

• Tinned beans, tomatoes, sweetcorn, peas, carrots and potatoes
• Tinned fish, corned beef, ham, chicken or a vegetarian alternative
• Tinned fruit, rice pudding and custard
• Pasta, rice, couscous, instant mash and porridge oats
• Long-life milk, juice and a couple of litres of squash
• Crackers, crispbreads, oatcakes and long-life wraps
• Jars of pasta sauce, curry sauce, jam, honey and yeast extract
• Dried fruit, nuts, seeds, cereal bars and a bag of boiled sweets
• Tea, coffee, hot chocolate, stock cubes and a small bottle of cooking oil

Buy the size and format you will actually use. A 2kg bag of rice is cheaper per kilo but useless if you have no way to cook it, so pair long-cooking staples with options that work cold or with just a kettle.

Water, Heat and the Manual Can Opener

Food is only half of it. Plan on three litres of water per person per day — two for drinking, one for food preparation and basic hygiene. For three days that is nine litres each, which is roughly six large bottles. Pets need around 50ml per kilogram of body weight per day.

Then think about how you will heat anything. A camping stove with a spare gas canister, used outdoors or in a well-ventilated space, is the usual answer. Never use a barbecue or camping stove indoors — carbon monoxide kills quietly and quickly.

And yes, the humble manual can opener. If the electric one dies with the power, or the tin has a ring pull that snaps, you will be very glad of a £2 piece of metal. Buy two, keep one with the food box, and test it on a tin before you need it. Add a bottle opener, a sharp pair of scissors, a torch with spare batteries, and a printed list of any medication the household relies on.

Store It Cool, Dark and Off the Floor

Heat, light and damp are what shorten shelf life. A cool, dry, dark cupboard is ideal — ideally somewhere that stays below around 20°C. Garages and sheds often seem convenient, but they swing between freezing and baking and can flood, which is exactly the day you will want the food. Under a bed or at the back of a hallway cupboard is often a better choice.

Keep everything in sealed containers or heavy-duty boxes with lids. That protects against mice, moths and damp, and it means you can lift the whole supply out of the way if water starts coming in. Store tins off the floor on a shelf or a pallet, and keep the box away from anything chemical — paint, petrol, cleaning products.

Write the month and year on the front of each tin and packet with a marker pen as it goes in. Stack oldest at the front.

Rotate, Review and Cook From It

A store cupboard is not a museum. Use it. Every six months — the clock changes in spring and autumn make an easy reminder — pull everything out, check dates, and move anything approaching its best-before date into your normal cooking.

Replace what you use, and check three things while you are there: the water is still in date, the batteries have not leaked, and the can opener still works. If you have a gas canister, weigh it or note the level.

The final step is the one most people skip: cook a meal from the box, using only what is in it and whatever heat source you have planned. Do it on a normal sunny Sunday. You will learn quickly whether your family will eat cold corned beef, whether the stove boils a pan of pasta in reasonable time, and whether you have enough teabags. Adjust, restock, and then forget about it — that is the whole point. Preparedness is not about fear; it is about making a difficult week merely inconvenient.