Yes, hyponatremia can be a serious and life-threatening condition. In addition to water, you've got to make sure you eat and get some electrolytes with your water.
There's been three fatalities that I know of -- not a lot, but that's a significant number 'cause not that many people die in the backcountry. Grand Canyon has an active campaign to remind people to both drink fluids AND eat to get electrolytes and calories.
An altered level of consciousness is one of the most noticeable symptoms followed quickly by slipping into a coma. Bad news if it gets that far.
George
None of the views expressed here in any way represent those of the unidentified agency that I work for or, often, reality. It's just me, fired up by coffee and powerful prose.
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