Quick Answer
Yes, you should filter water from a stream before drinking to remove bacteria, viruses, and other contaminants that could make you sick or lead to dehydration, which can increase the risk of hypothermia in cold water.
Assessing Water Quality
When searching for a stream to source water, look for signs of recent flooding, animal activity, or nearby agricultural runoff, as these can indicate contaminated water. If you must drink from an unsanitary source, purify the water using techniques such as boiling, chemical disinfection, or filtering through a portable water filter. Boiling is effective against bacteria and viruses, but can be time-consuming; chemical disinfection requires proper handling and storage of the disinfectant; filtering is a more efficient option, but requires a high-quality filter.
Filtering Techniques
A portable water filter with a 0.2-micron rating can remove 99.99% of bacteria, viruses, and other contaminants from water. Consider a filter with a built-in UV or iodine treatment for added protection against cryptosporidium and giardia. When using a filter, always follow the manufacturer’s instructions for maintenance, storage, and replacement of the filter elements.
Cold Water Survival Considerations
Dehydration can accelerate heat loss in cold water, increasing the risk of hypothermia. Drinking contaminated water can lead to gastrointestinal illness, exacerbating dehydration and further elevating the risk of hypothermia. When selecting a water source, prioritize purification and treatment to minimize the risk of illness and maintain physical and mental resilience in a survival situation.
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