Pre-filter your water. There are a number of ways to do this. Expedient water filters can be made from layers of cotton cloth or paper towels, or even from coffee filters. Here is one I used in Chad (probably before many of you were born) that worked quite well:
1. Take an old BDU pant leg, and tie the bottom closed. (In Chad, we used a fatigue pant leg, and tied it closed with string.)
2. Place a couple layers of cotton cloth in the bottom. On top of that, place a two-inch layer of powdered charcoal.
3. On top of that, place place a couple more layers of cotton cloth, and about a six-inch layer of sand.
4. On top of that, place another couple layers of cloth, and fill the leg to the top with dry grass or hay.
5. Suspend the leg off the ground, place a container underneath, and pour water into the top.
From here, there are a number of ways to proceed.
Instead of using a pant leg, I've found it best to use a 2 liter pop bottle. Cut the top off and build your strainer as described above. With solid sides the water cannot bypass the strainer and leak out thru the pants.
