My go to water filter is the Sawyer mini. It is reasonably priced, light weight, and you don’t have to hunch over at the water source like you would with something like a Life Straw. One suggestion I do have for it is to throw away the bag that comes with it. It is a giant pain to get any water into it. Grab yourself a 1 liter smart water bottle and you can save a bunch of time and stress.
When you are actually filtering water, every time you reduce the water by half- full to half, half, quarter, loosen the filter and allow air to fill the bottle. It will save you the struggle of getting the bottle smashed down super small. Check it out and enjoy not getting GI distress or some horrible illness.