I am a big fan of Sawyer filters. I have the mini, but have heard the squeeze is better due to the higher flow rate. It is essentially a small fiber membrane filter that screws onto the cap of either a bag or any standard pop/water bottle (Aquafina). You then squeeze the water through and it filters out all particles, bacteria, etc. I haven't seen it in any stores but bought a couple off Amazon and have used them quite a bit.
https://sawyer.com/products/type/water-filtration/