>>451251as deep in ground as you mind getting, preferably in an underground filtering source but thats unlikely.
just make sure its not a public beach or ocean sand which will be salted.
you want sand thats untouched by man and to know that theres nothing upstream that may have contaminated it, either way like that other anon said its the rough filtering portion anyways. also its the last ditch method, sometimes its better to get sick from water(or risk such a thing) than to die from dehydration.
