Xylem may be an unfamiliar name, but it's extremely simple to DIY.. and filters the water of pathogens at least as good as an expensive Berkey... Plus, the 'filter' is FREE and easily replaceable virtually everywhere...

As usual, you cant beat God's Nature...

Basically, A xylem filter is simply and effectively designed, which makes it one of the most viable water purification methods for preppers in third-world countries.

To make a xylem filter, you need a piece of clean, flexible tubing, a chunk of pine (or other conifer wood), and a bit of glue. Peel the bark from the wood, then attach the piece of wood into the end of the tubing with glue stuck on it. This lets water pass through the tube, and the liquid is filtered through the wood.

A xylem filter can remove at least 99.9 percent of contaminants. This method does have one downside: It takes a long time to filter water this way.

Here is a (technical) article on how to implement it and how it works.
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0089934

The results achieved in the conclusion of the above article reveals that up to 5 Liters per day can be achieved with a 1 inch long, 1 inch diameter piece of pine (conifer) wood. Five liters per day of drinking water is entirely adequate for one person.

Some helpful knowledge to store away for when you may need it...

Also, here are nine more methods for emergency water purification.

https://survival.news/2019-06-03-ways-to-purify-water-when-shtf.html