On a day hike, safe drinking water isn’t an issue. You can carry what you need. But when backpacking, you will most likely be using chemical water purification or filters to resupply yourself using natural sources of water. Both of these can fail at times. A filter can break or get clogged, and pills can be lost, damaged, or just not effective if the water you start with is too murky.
What you need then, if you want to be fully prepared when entering the wilderness, is a little knowledge, just in case. You need to know how to find safe drinking water, or make it. Here are some tips to remember.
Safe Drinking Water Tips
1. Use your map. See if there are farms or grazing lands or campgrounds upstream from where you are collecting your water. If so, be sure to boil it or use a heavier-than-normal dose of whatever chemical disinfectant you are using. Better yet, collect water somewhere else.
2. Use glacial melt water. If you collect water that is running out from under a glacier or is still near the glacier that it melted from, it is more likely to be safe. No guarantee, but in an emergency, it is likely better than the water from a cow pasture. If you have chemical purification tablets or a filter, it is more easily purified than muddy water (but allow lots of time for chemical purification of cold water).
3. Look at the surface. If there is a rainbow-colored sheen to the water, it may be toxic. If the color is from natural bacteria which are generally harmless, it will usually break apart when you poke a stick into it. If it doesn’t, it may be petroleum-based, and should be avoided.
4. Smell the foam. Foam on water can be from industrial pollution or detergents, in which case it isn’t really safe drinking water. But if the foam separates easily when disturbed and smells earthy, it is probably natural foam created by the plants in the water and the agitation of the current or waterfalls. In that case it does not indicate toxicity.
5. Look around. If you are near trail crossings or places where people camp, try to collect your water upstream of these areas. If it is a short walk, you may also want to get above any meadow where animals graze.
6. Treat clear water. If the water is murky, your filter may clog or your chemical treatment may not be effective. To solve this problem, let the water settle for a while in any container you have, and then pour off the clearer water after the dirt settles out. You can also strain water through a bandana or t-shirt to get the big stuff out.
In any case, look for the clearest water that is furthest from sources of contamination. Filter, treat with chemicals, boil, or take your chances. Safe drinking water is a necessity, so plan ahead.