One thing I never go without anymore on a backpacking trip is my Katadyn Hiker Pro water filter. I have used their old ones back when I was a guide so when I wanted one for personal use I went with what I knew worked. I picked this up a year ago and have been loving it since.
It comes with a pouch and a way to separate your clean lines from your raw/dirty lines.
I can fill up a Nalgene in less than a minute with minimal effort.
So if you go backpacking you should 100% get one of these. The weight of a filter is less than a full Nalgene, the math just works! I tried using gravity filters, but they don’t work for me in the rockies. I end up freezing my hands dipping them in to melting lakes to fill the reservoir. So simple to use, just get it.
Katadyn says: https://www.katadyn.com/us/ca/432-8018273-katadyn-hiker-pro-microfilter
Lightweight is your demand, but pumping performance is also a must. Our lightest backcountry filter, the compact Katadyn Hiker Pro, steps up as your best choice for safe hydration and great-tasting refreshment on the trail. Just a quick stop at a stream or lake nets you 1 liter/minute. The quick-connect fittings enable the simplicity of one-step filtering directly into most reservoirs or bottles. Plus, a cleanable filter protector allows on-the-go maintenance. You can refill your water supply quickly and get on your way to fun.