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How to make a basic clean earth filter (filtering water with gravel and dirt) - Wilderness Arena Survival
The most basic of water filters is the clean earth filter. Although not ideal for producing crystal clear clean drinking water, it does have the added advantage of filtering out some components that other filters are unable to remove. For instance, a basic clean earth filter can filter out 99% of radioactivity in water making it the go-to filter for nuclear emergencies.