Safe drinking water is paramount to having a successful trip.  Without it, you wouldn't be able to travel more than a few days.  Tripping involves extreme physical activity.  As with any activity that requires energy output, you're going to sweat and lose water.  Dehydration is one of the leading causes of health issues on trips, so it's essential you stay hydrated.  Force yourself to  drink water, even if you don't feel thirsty. 

   Boiling Water:  The old standby in purifying drinking water.  Boiling does the job, killing almost everything that can harm you, however it's becoming less and less practical with today's portable filter and purifying technology.  If you choose to boil water, you'll have to budget the time necessary to heat the water, and let it cool enough to be ingested.  Not practical if you plan to constantly be on the move.

   Water Filter:  A portable water filter makes getting clean water quick and easy.  Look for filters that have a high flow rate so you won't be wasting too much time or energy getting water.  0.5 - 1.0 liter/minute  is the norm here.  These filters will protect you against Giardia, Cryptosporidium and other harmful bacteria that could cause you to fall seriously ill.  These types of filters are a staple in most trippers packs as they're relatively lightweight, durable and inexpensive.  Two of the most trusted brands of filters are made by Katadyn and MSR