By Tom Glanville
Agricultural and Biosystems Engineering Extension Specialist
Iowa State University Extension
Safe drinking water is important to your family’s health. But how can you tell if your well and water system provide safe water? If your drinking water comes from a public water supply, the federal safe drinking water act requires that it be sampled and tested on a regular basis.
If you live on a rural acreage, however, your drinking water may come from a private well. If that’s the case, it’s up to you to make sure the system is properly inspected and tested for safety.
The quality of water from private wells should be tested annually.
Spring or early summer is one of the best times of year to test your well. Iowa gets most of its rainfall April through June. During this wet period excess water picks up bacteria, nitrate and recently-applied lawn and crop chemicals as it percolates through the soil. If the upper part of your well is leaky, this contaminated water may enter your well through these defects, bringing contaminants with it.
During late summer when the ground is dry, or in the winter when the ground is frozen, the same well may test safe. So if you want to get the most for your investment of time and money, test during wet weather. If your well water is safe during this time of year, the odds are that it will be safe the remainder of the year.
Water testing services are offered by private and state-operated laboratories.
Check your phone book or the web for private labs in your area, or contact the State Hygienic Laboratory, Iowa’s official state environmental laboratory, toll-free (800) 421-4692.
Accurate water testing requires proper scientific equipment and highly trained personnel. To be sure the lab you select is properly equipped and staffed with qualified personnel, ask whether it is certified by the Iowa DNR to perform water testing for public water supplies in Iowa.
There are many contaminants in the environment, and each requires a specific test. Testing for all of these would be expensive and time-consuming. Unless you know that a particular contaminant has been spilled near your well, start with tests for coliform bacteria and nitrate. These are two of the most common contaminants found in private wells. They are relatively inexpensive to test for, and are good general indicators of drinking water safety.
Careful sampling is required to obtain accurate test results. Samples for coliform bacteria, for example, must be collected in a sterile bottle. The lab will supply bottles that are properly prepared for each of the tests you need. Be sure to follow written directions supplied by the lab for collecting each type of sample. When sampling for copper, for example, samples collected early in the day usually produce the most meaningful results. Sampling location can be important too. Water for coliform bacteria testing must be collected in a clean indoor location to avoid contamination of the sterile bottle with dust and associated bacteria that can cause inaccurate test results.
Some counties offer private well testing programs. Contact your county board of health or county sanitarian to see if your county offers a well testing program.