75% of the Earth’s surface is covered with water, and 2/3rds of your body is composed of water, but go 3 days or so without any, and you’ll be joining the ranks of the ex-persons club.Unfortunately, most of what’s out there isn’t in a form you can consume without accelerating your demise. Neither blood, sweat, tears, urine, nor seawater are what you need, and will dehydrate you even faster if you foolishly try them as a substitute. Parasites, bacteria, viruses, cysts, and all manner of invisible nasties await you if you do find relatively fresh water that hasn’t been purified first.
Getting your hands on a military canteen, or simply a 1L plastic water bottle empty is a great start. If you can set up a series of three successive filters – say, three buckets or bowls with a drain hole in the bottom, with water going from one to the next in order – and fill the top one with pea gravel, the next one with sand, and the last with activated charcoal (wood charcoal from a campfire, and not wood that’s from a toxic plant!), you can filter out quite a bit of the crud, sediment, and discoloration and let it drip into what’s serving as your canteen. But it’s still not ready to drink yet.Under the heading of Primitive Purification Method #1, a 1L clear bottle of such clarified water, sealed, and set out in the sun from dawn to dusk, will use the sun’s natural UV rays to neutralize the beasties still present in your clarified water. Bottles much larger than 1L diminish the sun’s efficacy though, and you also need multiple bottles to supply your daily needs, all sun-baked appropriately, as well as a convenient sun-exposed spot to lay them. And your water will have to wait until it cools to be drinkable. But for thousands in temperate and tropical climates without other resources, it’ll do. Obviously, this isn’t going to work at the Arctic circle in the shortened days of most of the year. And sunlight eventually breaks down plastic bottles. Glass lasts a lot longer, but it’s heavy. *
A good deal quicker, if you have plain, unscented household bleach and a medicine dropper, is to put 2 drops of it per liter(quart) into that same clear but unpurifed water, shake it, and wait 30 minutes. If the water is unclarified (muddy, cruddy, etc.) double the amount of bleach per quart. If the water’s cold, rather than somewhere warmer than 60 degrees, double the wait time as well. You can drink pure water this way as long as the sodium hypochlorite (that’s the bleach part) holds out. Putting these instructions on a laminated card with an eyedropper attached, punching a hole through the corner, and banding it to the bottle of emergency unscented household bleach you buy annually for emergencies would be a splendid plan. At 15 drops per mL, and needing 1 gallon of water a day, a liter of bleach should last two people something like 500 days, or nearly year and a half.Which is probably about as long as a bottle of household bleach will retain its potency, which is why you should rotate yours into the laundry supply and replace the freshest bottle into your designated purification system every year. But there are varieties of Pool Shock, from pool supply stores, that would enable you to use your brain and a little chemistry math to recreate endless batches of household strength bleach from concentrated chemical, with due diligence. (Warning: The raw powder stuff is corrosive, and requires careful and proper storage and handling. But the chemical form lasts years longer than the dilute liquid variety.)
You can perform the same purification miracles with iodine, or potassium permagnate. The problems are that some people are deathly allergic to iodine, and potassium permagnate is rather hard to come by. If you have a source for those chemicals, and no one in your party has issues, there’s nothing wrong with using them. And with all of the above, your water will taste…crappy. If at all possible, after your water’s been safely made pure, put it someplace where it can breathe, uncapped, and/or pour it back and forth from a couple of very clean containers, to let some of your chemicals dissipate, and aerate the water, so that it tastes better. Powdered drink mixes in quantity for sheltering emergencies wouldn’t be a bad idea either. I’m partial to lemonade, but there are any number of flavors and varieties, some of which include a decent supply of electrolyte boosters as well. Just beware of the added sugar content in some.Then there’s the Cadillac systems: physical purification by filtration. Lifeboats and such use reverse osmosis and sunlight to draw the sea salt out of seawater. Slow, but flawless. You’ll need a lot of seawater, sunlight, and time, or a number of such units. Several companies, like Katadyn, make any number of small filters that use ceramic elements to achieve phenomenal purity, and the filter elements are the size of a water bottle or small flashlight, and last for something >10,000 liters. The small version uses a small hand pump. They make an expedition multi-filter size that look like a large bicycle pump, and turns out gallons instead of liters in a minute or two. And the Berkey folks make great stainless steel tubs which you simply fill and walk away from, and over time, the internal filters drip a day or more’s supply to the lower tank ready to draw off. The only drawback with any of these is price, usually currently somewhere around $250-350 and up, and the need, eventually, for replacement filters, because the old ones clog up over time internally, and spare anything is always good to have.
Lastly, of course, there’s the brute force method, assuming you have endless loads of fuel, a large pot, and someone to tend it. One makes pure water the same way nuns make holy water: you simply boil the hell out of it.For a person afoot, a small hiker’s filter and a small bottle of bleach and dropper would provide months of water availability, assuming one has access to water to purify.
For a base or homestead, a variety of methods of purification would be prudent, along with provision of rain collection barrels, springs, ponds, streams, cisterns, etc. and/or a well or three, to get and store as much of the stuff as you and yours might require. Imagine in your head that there’s no government to help you and no water company to pump yours, and start to think up how you and your devices and ingenuity would fill the gap left by their absence. For planning purposes, you drink and cook with about a gallon a day. Add sanitation, washing, bathing, and clothes cleaning, and you need to supply >100 gallons/person/day. Double that for watering crops. Calculate well, make appropriate provision, and plan prudently, folks.