Basics

An OSLT / Appropriate Materials type approach to Water Filtration
Essentially a bag made of Tightly Woven Canvas (Typically something like Cotton that is cellulosic and porous) that filters MOST particles out of water
- Probably not good enough compared to Microfiltration / Nanofiltration via Hollow Fiber Membrane based solutions like Lifestraw / Portable Water Filtration Pumps (such as those made by MSR etc)
If combined with Boiling (Essentially 100c Based Pasteurization , Modified Procedures like Tyndallization , and Autoclaving can be more effective against more durable pathogens/products such as spores), it can make safe water from a comparatively simple process

COTS Options