USGS CoreFacts
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Transcript:
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Welcome to CoreFacts, where we're always short on time and big on science. I'm Danielle Eganhouse.
If the ground filters water, is ground water always clean?
Water being drawn from a well was once precipitation that fell onto Earth's surface. It seeped into the ground and, over time, occupied the porous space in some subsurface material. Naturally, big particles that can be found in streams, such as leaf chunks, will not be seen in ground water. So, yes, big particles are filtered out. But ground water can contain other items that you can't see. Some are naturally occurring and some are human-made substances. Ground water can contain hydrogen sulfide or other naturally occurring chemicals. Ground water also may contain petroleum, organic compounds, or other chemicals introduced by humans' activities.
Contaminated ground water can occur if the well is located near land that is used for farming where certain kinds of chemicals are applied to crops, or near a gas station that has a leaking storage tank. Leakage from septic tanks and/or waste-disposal sites also can contaminate ground water. A septic tank can introduce bacteria to the water, and pesticides and fertilizers that seep into farmed soil can eventually end up in water drawn from a well. Or, a well might have been placed in land that was once used for something like a garbage or chemical dump site. In any case, it is wise to have your well water tested for contaminates.
And now you know. Join us again every weekday for a new CoreFact. For other CoreFacts, or for CoreCast, our in-depth science podcast, go to usgs.gov/podcasts. If you'd like to have a question featured on our show, give us an email at corefacts@usgs.gov or a phone call at 703-648-5600. Remember, long distance fees do apply.
CoreFacts is a product of the U.S. Geological Survey, Department of the Interior.
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