The greatest threats
Most reports agree that the greatest wa-ter-borne dangers to bushwalkers and ski tourers are from giardia, E. coli and blue-green algae. For both giardia and E. coli, this is because of widespread potential contamination, difficulty of detecting contaminated water and the relative ease of becoming infected. In the case of giardia there is also the nearly universal need for medical treatment to counteract the infection. The main threats from blue-green algae are in the severe impact of toxins, the fact that uncontaminated water can be hard to find, and the potential for dehydration resulting from inability to find suitable water.