There are a lot of equipments out there for backpacker that just add dead weight to your backpack but this is definitely a must have that will save you weight. Do you always carry at least 1-2L of drinking water with you? To save a couple of bucks, always opt for the 3.5L bottle water vs. 0.5L so you ended up always have to carry the left over water with you because it is too wasteful to throw them out?
It was painful carrying all these weight on top of your sac, isn't it? We thought this is how it has to be until we came across the SteriPEN that sterilize water from any water source so it is safe to drink without needing to boil. All we needed was a 1.5L bottle and a water source.
I can't tell you how great this is. BUT, we suggest you bring with you Iodine pills as back up. We lost our SteriPEN during our trip and ended up having to carry bottles and bottles of water when we track. Always good to have a back up plan!
You can buy this at MEC Canada or REI, US.