| Themes > Science > Earth Sciences > Geology > Water and Water Cycles > Water Pollution > How does water pollution occur? |
Although some kinds of water pollution can occur through natural processes, it is mostly a result of human activities. We use water daily in our homes and industries, about 150 gallons per day per person in the United States. The water we use is taken from lakes and rivers, and from underground (groundwater); and after we have used it-- and contaminated it-- most of it returns to these locations. The used water of a community is called wastewater, or sewage. If it is not treated before being discharged into waterways, serious pollution is the result. Historically, it has taken humanity quite a bit of time to come to grips with this problem. Water pollution also occurs when rain water runoff from urban and industrial areas and from agricultural land and mining operations makes its way back to receiving waters (river, lake or ocean) and into the ground. |
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