In fact, wastes such as manure actually improve the fertility of the soil. However, if the soil layer is very thin, if the soil has high permeability, or if the water table is very shallow, we may exceed its capacity to handle wastes.
The excess contaminants may then be carried into the groundwater system by rainwater, melting snow or irrigation water. Examples of human activities which may contaminate groundwater include agricultural and residential activities which involve fertilizers, pesticides and animal wastes, leaking fuel storage tanks, landfills and dumps, road salt, runoff from streets and parking lots, septic systems, disposal of sludge from municipal and industrial sewage treatment plants, and disposal of sewage from home septic systems.
Organic solvents, petroleum products, and heavy metals from disposal sites or storage facilities can migrate into aquifers. Pesticides and fertilizers can be carried into lakes and streams by rainfall runoff or snowmelt, or can percolate into aquifers. Human and animal waste. Human wastes from sewage and septic systems can carry harmful microbes into drinking water sources, as can wastes from animal feedlots and wildlife.
Major contaminants include Giardia, Cryptosporidium, and E. Treatment and distribution. While treatment can remove many contaminants, it can also leave behind byproducts such as trihalomethanes that may themselves be harmful.
Water can also become contaminated after it enters the distribution system, from a breach in the piping system or from corrosion of plumbing materials made from lead or copper. Natural sources. Some ground water is unsuitable for drinking because the local underground conditions include high levels of certain contaminants. For example, as ground water travels through rock and soil, it can pick up naturally occurring arsenic, other heavy metals, or radionuclides. Health effects of chemical exposure.
Chemical exposure through drinking water can lead to a variety of short- and long-term health effects. Exposure to high doses of chemicals can lead to skin discoloration or more severe problems such as nervous system or organ damage and developmental or reproductive effects. Only a small number of the universe of contaminants as defined above are listed on the Contaminant Candidate List CCL. The CCL serves as the first level of evaluation for unregulated drinking water contaminants that may need further investigation of potential health effects and the levels at which they are found in drinking water.
Learn about contaminants that are currently regulated. How EPA regulates drinking water contaminants. Skip to main content. Contact Us.
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