I have used a variety of water treatments, including a gravity filter (Seychelle), pump filters (Katadyn Hiker and Sweetwater Guardian), iodine, and Aqua Mira. Each of these methods do have their pluses and minuses, and they are all capable of producing "drinkable" water. For me though, I ended up setting all those methods aside and now I just use simple household bleach. All it takes is about 5 drops for every liter of water and about 30 minutes of waiting. So far I've yet to experience any ill effects, which is a step up for me (I got the runs once while using the Sweetwater filter, which ended up having a crack in the ceramic). Also, if you're really nervous about any particular water source, just boil it. The only time I ever feel truly comfortable drinking any water gathered from the outdoors is after boiling it. Another nice thing about bleach, other than simplicity and availability, is the small size and weight. A small eyedrop bottle holds more than enough bleach for most trips. Mine weighs 0.4oz (14g) full.

Here's what I use to store my bleach in:

Good luck to you,
Eric