Testing water

The following information outlines sample collection methods and sample types.


What should I sample for:

If the water is to be consumed by humans, at minimum sample for:
  • TDS (total dissolved solids)
  • Nitrate
  • pH
  • Fecal Coliform

Some contaminants may be present only during part of the year. To assess the year-round safety of your drinking water, collect the sample when contaminants are most likely to be present. Coliform bacteria and nitrates are most likely to be found during wet weather; late spring and early summer are the best times to test for these. Pesticides are likely to be present just after they are applied - late spring and early summer are the pest times to test for these, also.

 
Finding a lab to analyze water:
  • Look in the phone book under laboratories that specialize in agricultural industry.
  • Contact your local County Extension Office and ask them for labs in your area.
  • Contact your local NRCS Office.
  • Contact your County and State Health Department.

IMPORTANT: Contact the lab that will be running the tests before you start sampling, to obtain specific sampling instructions. Most testing laboratories supply their own sample containers and instructions for collecting, preserving and handling water samples. The following steps are general sampling instructions.

General Sampling Method:

Collecting Samples from Drinking Water:

  1. It is best to obtain sample bottles from the lab you are using, because the sample bottles need to be sterile. Make sure nothing but the water to be sampled comes in contact with the inside of the cap or bottle.
  2. Flush the water line leading to the tap. Remove the aerator screen from the faucet and open the tap to full flow. Let it run until water arrives from the well (usually signaled by a drop in temperature).
  3. Reduce the flow to a pencil-sized stream. Open the container, fill to 1/2 inch of the top and replace the cap immediately to preserve volatile compounds in the water and prevent atmospheric contamination.
  4. Many tests require that the sample be received at the laboratory within a certain time period to insure accurate results. Coliform bacteria samples must be received within 24 hours after collection. If the sample cannot be mailed or transported immediately, refrigerate it (do not freeze) and get it to the lab as soon as possible.

Collecting Samples from Surface Water (streams, lakes, ponds):

  1. Follow the steps above.
  2. Except the source will be different:
    • Take sub-samples at several different sampling points along the surface water source.
    • Mix the sub-samples in a clean, sterile container.

The information on this page was adopted from the Montana State University Publication "Groundwater, Water Testing Guidelines and Considerations."

 

View Text-only Version Text-only Updated: 08/28/2009