Filtering Water on the Trail

When you are hiking a long hike or in the back country, what is one of the heaviest items you carry?  Water!  You can’t even pay more to get “ultralight” water like you can for most other gear.  Each liter of water you carry weighs 2.2 pounds.  I have a three liter reservoir and if full it weighs more than six and a half pounds.  A gallon of water weighs over eight pounds. I recently did a hike where they recommended each person carry two gallons of water per person.  That’s over 16 pounds of water!  So, what is the best way to reduce carrying that much weight in water?  Getting water from sources along the way (if possible).   

If there are sources along your hike you can get water from, can you just drink it straight from the source?  Unfortunately, the answer is no.  Even when you are getting water from a spring, you should worry about animals drinking from the source and possible human waste near the source.  With more human activity on the trails, it is more and more likely.  Water sources on the trail could have things like protozoan cysts (cryptosporidium or giardia) and bacteria (E. coli, salmonella).  If traveling overseas, you might even have to worry about viruses in the water.   

So what to do?  Well there are a few things you can do.  First you can boil your water.  If you boil it for one to three minutes, the water should be safe to drink.  This may or may not be feasible considering you will have to bring a stove and fuel source.  You can treat the water with chemicals.  The tablets are very light and are effective against protozoa, bacteria, and viruses. Keep in mind, the iodine tablets are not effective against cryptosporidium so if that is a concern, get the chlorine based tablets.  The biggest drawback to the tablets is the amount of time it takes to purify the water.  Depending on the product, it can be between 30 minutes to four hours.  There are ultraviolet purifiers.  These relatively small devices go in your water, push a button and “stir” the water while the light is on.  When the light goes off, about 60 seconds later, the water is safe.  There are a few cons to this method, you must carry batteries, if the water is silty or cloudy you must prefilter it and you will have to do multiple treatments for large quantiles of water.   

You also have multiple choices of water filters.  Keep in mind, these are not household filters.  Those are not designed to filter things as small as cysts or bacteria.  You need a filter that filters to .02 microns to remove those.  Filters can be as simple as a “straw” system that allows you to drink directly from the water source.  They can be as complicated as a gravity system where you have two containers for the water.  One container has the prefiltered water and that feeds through a filter to the second container.  These are great to do a large quantity of water, but it will take time.  There are also hand pumps with prefilters that allow you to pull water from relatively shallow sources.  There are too many filter options to go into all of them here.   

When selecting your water purification system, make sure you understand what you need to filter for, how much you will have to filter at a time and how much time you will have to filter the water. Price also will play a part when choosing your system. Prices range greatly between purifiers and filters.  Then do some research to get the system that works best for you.  I also always recommend having a second option with you.  It’s always a possibility your filter could break or your UV purifier runs out of battery.  With just a few precautions and a little practice, you can safely drink the water around you on the trail!