All of us know about the "Berkey(r)" filters, but few can afford them. This article shows how to build a working ceramic filter system for much less money.
https://survivalblog.com/do-it-yourself-ceramic-water-filter-by-the-architect/I've not done any research to find the filter elements in local stores, so you will want to check in your area first. You could also find these online, but I have no recommendations, other than that they be both a ceramic and a carbon filter.