This is the second season I have been using Aquamira Chlorine Dioxide drops in combination with the Aquamira water bottle filtration system. This system is very light weight and extremely effective.
The drops basically kill everything in the water. However, it takes 4 hours to kill Crypto. This is one reason I use the filter system in combination. The filter will get rid of Crypto, and many other things including metals, pesticides, etc... It also gets rid of the chlorine from the drops.
The drops also kill viruses, which the filter cannot get rid of. I feel the combination of the drops and filter system is one of the best systems on the market.
There are several reason's I prefer a bottle over using a bag while backpacking. One issue I have is that I never know how much water is left in the bag without taking it out of my pack, which is a pain in the neck. A bottle is much easier to fill than a bag too. I have not come across a decent filter system for use with a bag, other than the larger bulky styles sold at REI.
I am considering getting a Steripen, or MIOX for next season. That is if I can come up with some extra cash. I am leaning more towards the Steripen because it kills everything in just a couple of minutes, whereas the MIOX takes 4 hours to kill Crypto. The Steripen may eliminate the need to carry a filter. However, it will not get rid of pollutants, metals, pesticides, etc... Thus, carrying a filter may still be a good idea.
By the way, I have the 22oz. bottle and the 32oz. bottle. The 32oz. bottle seems to leak around the top. I have to use it more to determine if the top was just on too loose, or it is truly a poor seal. However, I don't have any issues with leaks in the 22oz. bottles.
I like the Aquamira water bottle filter system and the Chlorine Dioxide drops. I highly recommend them for anyone looking for a great water treatment system, which is also light weight.