Not all water on earth is polluted, or more correctly, not all water IN earth is polluted. Many people rely on wells drilled into the ground for their water, and this water has generally remained untainted by human activity (except possibly in the pipes during transportation). In some agricultural areas, there is concern that pesticides may leach through sandy soils and contaminate some of this underground water. In other places, there is concern that too much water has been drawn out for irrigation, and that the wells will go dry. The good news is that water can be unpolluted by filtering, boiling, or by chemical treatment, so drinking water supplies are safe most of the time.
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