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General guidelines for sampling water for lab testing

Contact a certified laboratory for questions regarding water sampling. The sampling procedure depends on what you want to test the water for.

  • Bacteriological analysis is used for detecting bacteria such as coliform bacteria
  • Chemical analysis is used for detecting metals (iron, manganese, lead, heavy metals etc.), minerals and salts (calcium, magnesium, sulfates, sodium, nitrate, hardness, alkalinity etc.), oil, pesticides and chemicals

General guidelines for sampling water for testing at a lab

Bacteriological Analysis

Most labs will provide a sterile container for the water sample. If the sample is from a public water supply make sure to get a container that contain a chlorine inhibitor. Before sampling water, remove the aerator from the faucet if it has one and sterilize the end of the faucet with a flame. Remove the sample container cap and make sure you do not touch the inside of the cap or container. Let the water run for 30 seconds and then fill the bottle to the indicated line or near the top and immediately put on the lid. Send or deliver the water sample to the lab.

Chemical Analysis

The water for testing should be sampled at the well site or at a tap inside the house into a clean 6–12 ounce plastic or glass container or as instructed by the laboratory. Make sure the containers are thoroughly rinsed and do not use containers that have had milk or carbonation in them. Run the tap for 30 seconds before taking the sample. Fill the container to the top and immediately put on the lid. Note: when sampling for lead or other metals that you suspect originates form the pipes in the house, do not run the tap before taking the sample. Lead testing required a water sample that has been sitting undisturbed in the pipes.

For ponds, dugouts and other surface water sources, take the sample away from the shore. Avoid algae, soil or other foreign materials. Combine several water samples from different depths and locations to obtain a composite sample.