High quality cotton coffee filter

That’s the first time I ever heard of them. I do see them on Amazon.

Yep .. though not sure which has the 20-50 micron pore size

I found one made nearby; however the product description stated that it had a large pore size to allow the flavoursome coffee oils to filter through 🙂. Oh well. Try again.

Coffee isn’t clear.

You can probably find reusable coffee filters at upscale grocery stores. The little GSI pour-over coffee filter would also work and you can use it to make coffee. For those not understanding pre-filtering, it’s for getting the large chunks out before using a real water filter or chemicals.

I’ve tried filtering coffee as a test. Unless you use a paper filter, you’re going to get oils. Generally not a problem with water.
I found my Thermarest sleeping pad bag fits nicely inside of a CNOC water bladder. Overlap it and you can seal it off letting it flow through a water filter. Actually most of the water goes through the seams. Something better can be found. A cotton bag would probably work better. I’ve looked at actual lab filter bags, but haven’t found a source I was happy with. A bandanna is a lot cheaper. A small bag of activated charcoal at the bottom will give you a compound filter, but isn’t necessary and adds a little weight.

This is the info I referenced that was just sent via email

“I use two tricks to pre-filter cloudy water, whether I’m using a chemical method or a squeeze filter method.

The first is a high-quality cotton coffee filter, and the second is a typical cotton bandana. You’ll need an elastic hair tie or 1/8″ shockcord loop as well to secure the fabric over the mouth of a water bottle – this makes it easy to pour cloudy water from another container through these pre-filters into your bottle.

High-end cotton coffee filters have small pore sizes – on the order of 20 to 50 microns (as a frame of reference, paper coffee filters are at the low end of this range). They can effectively filter out particles about 1/5 of the diameter of those pores – 4 to 10 microns – the size of typical silt particles found in spring runoff.

Bandanas, on the other hand, typically have pore sizes in the range of 50 to 100+ microns. They’re not very effective at filtering fine silts and clays that you’ll find in some runoff regions. However, they are very effective at filtering out the larger organic (char) debris found in the mud flows of runoff from wildfire burn scars.”