1. Live off supermarket food as long as possible.
A small post-apocalyptic community won’t need to relearn the basics of agriculture immediately – the huge reservoir of preserved food in supermarkets will offer a grace period before successful farming becomes a matter of life and death. An average supermarket can feed a single person for 55 years, 63 if you eat the canned cat and dog food too…
2. Open a can without a can opener.
The last thing you want to do with your scavenged can of food is try to hack into it with a knife and risk slipping and cutting yourself in a world without antibiotics. But opening a can without an opener is astoundingly easy, if you just think about how a can is made. A cylinder of tin-coated steel is capped with a disk of metal by folding over the edge – so all you need to do to open a can is wear away only around a millimetre of metal in that protruding lip. Simply grind the end of the can on an area of concrete and the lid will soon pop off.
3. Harness fire.
You won’t need to rub sticks together to ignite a fire in the immediate aftermath; even if you can’t find any matches or lighters, everyday objects can be repurposed in surprising ways. For example, crack open a fire alarm to release the 9V battery, and rub the terminals against a fluff of steel wool from under any kitchen sink or abandoned supermarket. The thin wires have high electrical resistance and will heat up and burst into flame.
4. Make yourself a stove.
A ‘gasifier stove’ makes very efficient use of wood fuel and can be built with only simple tools and a few old tin cans. Wood is burned in the inner can, with holes at the bottom to draw air through the fuel, but importantly a second ring of holes at the top. This re-introduces oxygen and ignites the flammable vapours and gases given off by the wood as it breaks down. This gasification process can even be used to power a cars and trucks.
5. Sterilise water with bleach or UV rays from sunlight.
Water can be sterilised by boiling. But to save fuel diluted kitchen bleach or even swimming-pool chlorine is very effective. Even a clear plastic bottle can kill waterborne pathogens in a day by exposing them to UV rays in the sunlight – a technique recommended by the WHO known as SODIS (solar disinfection).
6. Always wash your hands.
Huge numbers of people die every year from infections picked-up through ‘faecal-oral’ transfer, which is as delightful as it sounds. The simplest way to prevent this is to keep washing your hands. Soap can be made ludicrously simply: boil animal fat with seaweed ashes and lime (from roasting chalk or limestone).
7. Sort your shit out.
In the longer term, you really need to make sure that your water source isn’t contaminated by your own, or anyone else’s, excrement. Make sure any latrine pits you dig are at least 20m from any well or other water source.
The key trick for waste water treatment is to force human pathogens to compete with environmental bacteria, in a sludge tank or reed bed – a contest they are poorly adapted for and will lose. Manure is a wonderful way to maintain the fertility of your farming fields, but human stuff must be properly treated first.
8. Grow your own food for when the supermarket stuff runs out.
All of humanity essentially eats a staple diet of grass – the cereal crops wheat, rice and maize. These fast-growing species provide condensed dollops of nutrition in their grain, but it must be gathered by chopping the whole stalk down and then threshing it to knock-out the seeds. A milling stone (perhaps turned by a windmill) is like a technological extension of our own molar teeth, grinding the grain into flour so that we can cook it in bread or pasta to unlock the nutrients for our digestion.
The key to agriculture without artificial fertilisers is to maintain the fertility of your fields by alternating between cereals and leguminous plants like peas, alfalfa and soy, which return nitrate nutrients into the soil.
9. Scavenge diesel-fuelled generators from building sites or roadworks.
After the grid goes down you’ll want to create a local power network for yourself. In the immediate aftermath you could scavenge diesel-fuelled generators (try roadworks or building sites) but in the longer term you might jury-rig waterwheels or windmills, fitted with the alternator cannibalised from an abandoned car to generate electricity. This can be used to recharge deep-cycle batteries (such as from caravans, mobility scooters or golf carts) for storage and keep your life electrified.
10. Use electricity to make some basic chemicals.
Electricity is also a great way of providing substances that are difficult to produce purely chemically. Splitting water gives you hydrogen and oxygen, and electrolysis of brine produces chlorine – essential to make bleaches for clothing, hygiene and disinfecting drinking water.
11. Redevelop a chemical industry.
One of the most vital classes of chemicals throughout history has been the alkalis, such as potash (potassium carbonate) soaked out of wood ashes or soda (sodium carbonate) soaked out of seaweed ashes. These are critical for reacting with fats and oils to make soap, disassembling plant matter to make pulp for paper, and in the production of glass.
Before the late nineteenth century and the exploitation of coal and then crude oil, the source of chemical feedstocks – acids, alcohols, solvents, tars – was by baking timber in an air-tight container and collecting the vapours released.
12. Keep your car running with wood.
Once all the diesel and petrol have run-out you can keep your car and vital machinery running with wood. Timber can be partly-combusted with limited oxygen supply in a process called gasification. It releases flammable hydrogen and methane gases, which can be piped directly into the engine cylinders.
During the Second World War, a million vehicles were adapted to run on wood gasification (the German army even adapted tanks to be wood-powered), and in Scandinavia today electrical power stations use this same efficient process.
13. Begin relearning the world yourself.
Selected tips on how to keep yourself alive and begin rebuilding civilization will only get you so far. You’ll also need to begin relearning how the world works for yourself.
The most important piece of the modern world to preserve through the cataclysm above all else is scientific enquiry. Closely observing the world around you and running experiments will allow you to decide how to go about restoring civilisation. The machinery of science is what built our modern world, and it is science that you will need to rebuild again.
Lewis Dartnell’s new book The Knowledge: How to Rebuild our World from Scratch is out now.
You can also explore a load of related material, including how-to videos, at the-knowledge.org.