It is always smart to minimize the risks of drinking contaminated water, whether or not you are planning on treating the water in some way. This is especially true for those taking a more relaxed approach to water treatment. But even if you decide to rigorously treat your water, you still want to collect it from the safest possible sources.
What follows is my advice on this subject, a synthesis of my research, the first three pieces of which advice go against common practice.
— There is no basis for believing that fast moving water is uncontaminated. In fact, turbulence can stir up the nasties. One qualification: in the spring, with water temperatures low and volumes high from runoff, there is potentially less of a threat. A valuable piece of advice from an unknown source summarizing this perspective: “the solution to pollution is dilution.”
— An extension of the above advice is to drink lake water when available, if the bottom consists of rocks and sand. A thick, mucky bottom indicates stagnation. In addition, larger bodies of water act as settling basins. Drink from the outlet stream where the settling influence is greatest. [Note: It is sometimes claimed that taking water from the surface of lakes is better because it has been subjected to the cleansing influence of ultraviolet light. This might be true, but my research has not corroborated it one way or the other.]
— Cold water is no guarantee of non-contamination; cold water that appears clean might not be. The warmer the water, the higher the levels of potential contamination. In the winter and early spring, the microorganisms of concern die off or are less of a threat. As the water temperatures go up, the microorganisms start growing, and, by midsummer the potential threat is at its peak.
— Good spring water or very small streams are the hiker’s best source of drinking water. Don’t automatically assume, however, that a spring is clean; it depends upon its source. Springs and streams with any noticeable smells or extra plant and animal life should be treated with suspicion.
— When drinking from springs, seeps and streams, the higher the elevation of the watershed and the smaller the watershed the better. With small streams, walk upstream a bit to get a sense of its character and see if its source is a spring
— Melt snow taken from remote snow banks in higher elevations or from freshly fallen snow. Do not assume that all snow is safe.
— Drink as much water as you can from known clean sources at the trailhead before starting out and upon returning. Also, when in the backcountry, drink as much water as you can from the highest quality sources (often referred to as “cameling”).
— If high quality water sources are not available for a period while hiking, do not compromise your health by drinking from questionable water sources. Humans can generally go without water for many hours or even a day or two without jeopardizing their health. Obviously, one’s sense of comfort (mental and physical) will likely be compromised.
— When possible, ask knowledgeable people about their experiences with water sources in an area. I regularly come across experienced backcountry travelers who say they have been drinking backcountry water for years without treatment of any kind. I acknowledge that this is not a scientific sampling, but it is interesting nonetheless.
With which of the above pieces of advice do you agree? Disagree? Would like to qualify or add to?