Pollution is the presence of substances in the air, land, or water that can degrade human health and environmental quality. These substances may come from many sources, but some of the most serious pollution problems are the result of unwanted by-products—commonly called wastes—from human activities. Waste water, ground pollution, fertilizers, road treatments, all contribute to the pollution in our waters.
Household water is carried to treatment plants where it is filtered and chemical waste is broken down. Water that has been treated is released into river, lakes and oceans. The water molecule moves back into the watershed after a trip through the treatment plant.