What exactly happens when your water runs low? Dr. Mark Davenport, a Traverse City sports medicine physician who served as a team doc at the Barcelona Olympics, shares the details.
Electrolytes are very dependent on fluid status, so as you lose water, your concentrations of important elements like potassium and sodium will increase--cramping is a common result. You also sweat less to conserve water and eventually, you will not sweat with extreme dehydration.
As you become severely dehydrated, your heart rate increases as the body pumps more blood to compensate for reduced plasma. Also, your core temp increases as your body becomes less able to regulate body processes--a problem exacerbated by reduced sweating. In a survival situation, after three days without water you might still be alive, but would likely be so debilitated--possibly hallucinating and stumbling--that you would not be able to help yourself.
Simple, fast, light and idiot-proof--all reasons why Sandy Graham, owner of Traverse City's Backcountry Outfitters (231-946-1339) likes the MSR MiniWorks EX water filter. His tips for any water filter: avoid silty water whenever possible and pre-filter to extend the life of the filter in the pump. (Tricks here: buy an inexpensive fuel filter and duct tape it to the water intake, or pour water through a coffee filter prior to running through the pump.) msrcorp.com/filters/longevity.asp.