Lost in the wilds? How to purify water with your pants

Never drink water directly from a stream. Instead, purify it first.
Photo courtesy of David Niblack, Imagebase.net

If lost in the wilds, you may run out of canteen water and need to drink from local sources. Hopefully, you’ve brought along purification tablets or filters. That isn’t likely on a day hike, however, so you may need to improvise. The simple solution: Use your pants leg.

Denim makes for a great bag to create a filter, but really any material will work, whether it be the leg of rain pants or a canvas bag.

The steps for making a water filter with your pants include:
g Cut off a pants leg where it meets the seam for your other pants leg.
g Tie off the end of the pants leg bottom. This will need to be strong enough to hold weight.
g Gather small stones (gravel works fine) and sand, or at least have them near where you’re working.
g Hang the pants legs from a tree. Rope or a belt can be used; poke holes 180 degrees from one another bear the tip of the pants leg for the rope or belt to be tied. The branch and tie-job will have to be strong enough to bear weight.
g Visually divide the tied-off pants leg into six equal horizontal sections.
g Place the small stones in the first horizontal section at the pants leg’s bottom.
g Place sand in the second horizontal section above the stones.
g Place a layer of small stones in the third section.
g Place sand in the fourth section.
g Place stones in the fifth section.
g Slowly pour water into the sixth section of the pants leg.
g Place a cup below the pants legs where water drips from it; you may need to hold the cup in place with rocks so that it doesn’t fall over in the wind.

This filter only removes large contaminants from the water. To kill bacteria and viruses that may be in the water, boil the water in the cup to have drinkable water.

Read more about day hiking with children in my Hikes with Tykes guidebooks.

How to find drinkable water if lost in wilds

Avoid directly drinking water from a stream, pond or lake.

Use spring water; always boil, filter

If you’re lost or forced to stay a night in the wilds, avoid using local sources of drinking water. Still, sometimes you must take a calculated gamble or dehydration will set in.

The first challenge is to find a source of local water. Spring water is the best discovery, as it runs the lowest risk of being contaminated. Your next best bet is finding flowing water from a stream that is high in the mountains or hills, as it’s more likely than not to be clean as it is close to its source, which is melting snow. Flowing water at the bottom of a mountain or hill is your next best choice. Still water on low-lying land is your worst.

Finding water in a desert
If you’re not lost but simply stuck in the wilds for a night due to an injury, check your topo map. Well-known springs often are marked on them.

In a desert, finding water at all can be nearly impossible, but it is out there if you know where to look. On seasonal waterways, the thicker and greener the vegetation the more likely the chance that you’ll find standing water nearby. A grove of cottonwoods and willows almost guarantees that ground water is nearby. If there isn’t any, dig in the cool sand under a willow, and you may find water only a few inches down. Puddles also may exist under large overhangs and in shaded rock crevices, particularly if they are on a hill’s north side.

To collect the water, simply use one of your canteens or water bottles. Don’t dump out good water that you’ve carried in, however, but combine it with water in another partially filled canteen. If the water source is too shallow for a canteen, spread your handkerchief across the water surface. When the handkerchief has absorbed the water, wring it out into your canteen.

Once you’ve collected water, you need to “clean” it before imbibing. There are three options: use water purification tablets, boil it, or use a water filter.

Boil at least 5 minutes
A variety of water purification tablets are available for sale, so follow the instructions on each packet for the best results. Generally, though, tablets have to sit in the water for at least 30 minutes – and if the water is cold, the tablets may need to mix in it overnight. Tablets always will leave a little aftertaste, ranging from iodine-like to a tart flavoring. Be aware that if you or your child has thyroid problems, water purification tablets may contain iodine and probably should not be used.

If boiling, do so for at least 5 minutes. This will kill Giardia and all but the hardiest microscopic bugs. Boiling won’t remove chemical contaminates, however. In addition, if water is cloudy and you can’t see any life such as fish or amphibians in it, boiling probably won’t make it safe. When boiling water, do not do it in your plastic canteen or water bottle. The plastic likely will melt, or you won’t be able to touch it when hot. Given this, you may want to add “cooking pot” to the list of items for your backpack, but I’d only do so if you’re planning a long hike into the backcountry.

A number of water filters exist, all using different filtration systems and coming in different sizes. Whichever one you choose, make sure the filter pores are smaller than 0.2 microns. Anything larger will allow nasty bacteria to get through and remain in the water.

What are the advantages of each filter over the other? One that lacks iodine won’t remove viruses, so you’ll need to use water purification tablets or iodine anyway. A carbon or charcoal filter will remove chemicals that purification tablets and boiling won’t get rid of. Reverse osmosis filters are best of all, removing almost everything bad and even desalinating sea water. Unfortunately, they’re bulky and expensive, and you probably aren’t going to carry one on a day hike let alone a camping trip.

Read more about day hiking with children in my Hikes with Tykes guidebooks.