State University Extension
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How to Take a Water Sample
Water may appear clear and pure, but water from wells or other sources
may contain dissolved minerals and other substances. Generally, ground
water provides a good supply of safe water, that doesn't need much
treatment. If you are a private well owner, you need to test your water
supply to insure the well provides safe, high quality water.
With the advice of your county Health Department or Cooperative
Extension office, decide what tests are needed for your water supply.
After selecting the tests, choose a lab to test the samples.
Steps required for taking a water sample will vary for different tests.
Timeliness and cleanliness are important when collecting any water
sample. Use the sterile collection bottles the lab sends you and not
your own bottles to take a sample. Labs often will only accept samples
taken in their collection bottles. Also complete all the forms the lab
requires to process the sample.
A water sample needs to be submitted to the lab within 48 hours of
collection. In some cases it must be kept cold prior to testing. Care
must be taken to prevent anything but the water from contacting the
inside of the bottle or the cap. Contaminants are often present in
small amounts. Careless sampling prevents accurate test results.
For most water tests, follow these steps when collecting a sample:
- Take the sample close to the pump, before the water goes through a
- Do not take the sample from a swing-type faucet. Inspect the faucet
for leaks. Select another faucet if there is leaking.
- Remove the aerator.
- Disinfect the faucet with bleach or a flame.
- Run the water several minutes to clear the line.
- Take the sample midstream. Do not touch the sides of the collection
bottle, the opening or inside of the cap.
- If needed, store the sample in the refrigerator before taking to the
- Submit the sample within 48 hours of collection.
- Transport the sample in a cooler or ship in an insulated container.
Some tests, such as lead, require the water stand in the pipes
overnight before taking a sample. Again, follow the instructions
provided by the lab or your Health Department.
Testing for Volatile Organic Chemicals
When collecting a sample to be tested for volatile organic chemicals
these additional steps should be followed:
- Reduce water flow to prevent excess air in the sample.
- Remove all air from the collection bottle by filling it to almost
overflowing. Again, timeliness and cleanliness are extremely important
to prevent false results.
Testing for Pesticides
Samples for pesticide testing must be taken so they will not
deteriorate or become contaminated before reaching the lab. Contact the
lab testing the sample for complete instructions and a collection kit.
Specific steps needed when testing for pesticides include:
- Collect the sample only in the amber colored bottle provided. The
dark glass prevents light from degrading the sample.
- Cap the bottle with the Teflon coated lid. The special lid prevents
false positive results caused by certain plastics.
- Keep the sample refrigerated, preferably 35 degrees to 38 degrees,
and submit it to the lab within 48 hours. If shipping the sample, pack
the sample in ice and ship in a Styrofoam or other insulated container.
If test results show an unacceptable contamination level you should
seek the advice of a professional. In most cases a second test will be
taken before recommending possible treatments.
Keep a record of your water tests. The record should include the date
and the test results. Comparing recent test results to previous test
results might point out problems you may not have noticed. Water test
records are often needed for property sales. Records also support
damage claims from outside contamination, such as from chemical spills
For Further Information: for
further information on water testing or possible contamination
suspected in your area, contact your local Health Department or county
Cooperative Extension office.
This information comes from Purdue Extension bulletin WQ3, How to Take
a Water Sample.
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educational purposes only. References to commercial products or trade
names does not imply endorsement by MSU Extension or bias against those
not mentioned. This information becomes public property upon
publication and may be printed verbatim with credit to MSU Extension.
Reprinting cannot be used to endorse or advertise a commercial product
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are open to all without regard to race, color, national origin, gender,
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status. Issued in furtherance of MSU Extension work, acts of May 8 and
June 30, 1914, in cooperation with the U.S. Department of Agriculture.
Thomas G. Coon, Director, MSU Extension, East Lansing,MI 48824. This
information is for educational purposes only. Reference to commercial
products or trade names does not imply endorsement by MSU Extension or
bias against those not mentioned.
information.was reviewed as
of June 2008. For more information about the contents please
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