Filters work pretty well. Years ago, the old MSR Pump was my go-to (before then, there was little reason to treat water…,) I believe I gave it away after 10 years of non-use.
I switched to Aqua-Mira with a small bottle, maybe ten uses, of bleach. But, I got sick twice using AM drops. No problem with the treatment, I was badly dehydrated and couldn’t wait the full 4 hours. I tried several others: AM tablets, etc… All had the same problem. I had to carry at least 2 hours of cooking water as well as the water to drink. AM drops/tabs are NOT the lightest option when you consider an extra Liter of water. We are talking over two pounds of weight for the additional water.
I switched to the old mUV. It worked well until it no longer charged. Never got sick with that one.
I switched to a Sawyer, later a Sawyer Mini. They were just painful to use. I always spent at least 10-15 minutes refilling my bottles, even in a hurry. But, the bag was handy for carrying an extra 16oz of water, and, you can just squeeze it into your mouth. However, the threads are slightly different from everybody else…and the hose gasket has an odd way of becoming “lost” when you need it. The mini was better, but still a full 2.5L bottle still does not fit without some leakage. I froze one in the spring one year and canceled the trip, do not let them get cold.
I stumbeled across a Steripen Salesman at a sports shop…I bought the recharge kit on the spot. The rechargeable batteries and solar panel/box bit the dust when I found a $15 set of lithium 123’s worked far better, were lighter and more reliable. I lost one on a mountain, the replacement was an Opti. It worked well and could even double as a flashlight. It takes about 1 minute to get a drink out of a stream. Watering hole stops were less than 5 minutes for two bottles: adding water to a bottle, “sterilizing”, adding some flavorings & electrolytes, shake it all up and drop it into my pack (after drinking the first one) and go.
Soo, in sumary, I use boiling water at camp, usually. Cocoa, coffee, tea, etc. Boiling will always work unless the water is contaminated with a non-biologic. But, it can take a bit of fuel iff you don’t need morning coffee/tea or evening cocoa.
Chemicals are heavy when you consider the extra water weight for “cooked” water.
Filters are very light weight, but, the weights touted are empty, not in use. Hoses are fiddly and heavy. Hanging water bottles (or some source for dirty water, like a funnel with a tube) get rather complicated for other than overnight use. And, they are strictly 3 season use. A frozen filter will ruin your trip.
The Steripen Opti works better as the best compromise of weight (requiring no extra water,) the most reliable (a spare set of batteries will allow me 4 weeks of clean back-country water, “freeze” proof for all the temps I need, the easiest in use and the fastest at a stream/water hole. There are lighter methods. There are faster methods. There are more reliable methods.Works for me…