Right, Jimshaw,
1. catching rainwater runoff from a tarp or just a groundsheet layed out on the ground. I put catchments under each corner of my tarp. A catchment can be the pack cover, a garbage bag, a Ziploc held upright by putting a stone in the bottom, a cooking pot, a well sealed stuff sack... whatever.

2. In places like the Gila Wilderness (and most places, actually), the soil is gravelly and sandy near creeks. When the water is turbid, it is an easy matter to dig a hole near the creek. It will fill quickly with water. The first fill may be turbid, but the next fills will clear up quickly. Dip the water out until it clears.

3. Gather turbid water in the evening and let it settle overnight. Pour or dip clear water off the top - carefully - because the settled material is easily disturbed.

4. Carry chemical treatments - a few Aquimira or iodine tablets - to use when the filter tanks.