This hydration kit is what I take for filtering water on backpacking trips. It’s compact, simple to use, and very lightweight.
I’ve made quite a few gear upgrades since the end of last year’s backpacking season, including a tent, sleeping quilt, rain jacket, insulated puffy, GPS device, and a camera. Beside replacing broken or lost gear, most of these items were upgraded so I could carry less weight while backpacking.
If you are looking for a lightweight and inexpensive cookset for camping or backpacking, the Survival Hax Camping Cooking Kit is worth considering. The full kit weighs less than a pound, and everything nests together for ease in carrying in the included stuff sack.