Sure thing. Grab a sturdy stick, a few inches long, and cut it in half so it’s a tube. Find some clean river gravel, wash it, and sift it out. Then get a layer of charcoal—any kind, just crush it so it’s fine. Next layer is sand, then a handful of fine dirt. At the very top, slap a piece of clean cloth or a handkerchief. Thread the stick through the layers, seal the ends with some twine or a bit of clay, and you’ve got a basic filter. Pour the water in slowly; the cloth catches the larger grit, the gravel and sand strain out particles, and the charcoal helps with taste and some microbes. Test it, adjust the layers if the flow’s too slow, and you’re good to go.