| Sources of Water Contamination
As water moves through the hydrologic cycle, its quality is affected by both natural processes and the action of humans. Water is contaminated by runoff from stormwater or snow melt, by seepage through the soil, and by atmospheric transport. Contaminents enter water supplies through landfills; deteriorating, underground storage tanks; industrial waste; agricultural fertilizers and pesticides; animal feedlots; highway de-icer runnoff; faulty septic tanks; hazardous waste sites; and leaching from pipes, solder and pipe joints. Individuals and their families also contribute to the pollution of water. Car oil and solvents are dumped on the ground. Excess lawn fertilizer runs off into storm sewers. Paint thinnner and chemicals are flushed down the drain. People forget that water is continuously recycled and that anything added or put into the water supply or ground can potentially end up back in our drinking water. |
Pollution Of Groundwater
Pollution of ground water is a very serious problem, because in the United States, 80% to 90% of the total available water supply comes from the ground.
For many years it was believed that ground water was "safe" from being degraded by what we did on the surface of the land. We believed that the ground would somehow magically cleanse itself, protecting our ground water from contamination. Since groundwater typically moves very slowly, the consequences of our actions on the land's surface did not appear immediately; and it has only been during the last few years that people have been wondering how the pollution occured.
Groundwater from deeper aquifers is usually less vulnerable to contamination than that from shallow aquifers; but deep drilling for exploration, injection of waste; and improperly abandoned wells and test holes, as well as natural events, cause contamination in the deeper aquifers.
Toxic Chemicals In Water
There are approximately 300,000 known chemical compounds currently in existence for which we have toxicity data on only a small percentage. For example, 400 of these known compounds are known animal carcinogens. The rest remain uncertain. A dramatic rise is occurring in the levels of toxic chemicals being found in ground water, and exposure to some of these chemicals over extended periods of time may cause chronic health problems. Due to lack of conclusive health effects research, the high cost of analysis and detection, and the thousands of chemicals in existence, drinking water standards have been recommended for less than 100 of these 300,000 components.
Pollution of Rural Groundwater
In a 1984 U.S. Environmental Protection Agency study, bacterial contamination was found to be the most common problem in rural water supplies. Because the primary sources of bacterial contamination are from animal or human waste, this fact supports the theory that contaminants from the surface are finding their way into our rural water wells.
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