Testing And Treating Well Water For Bacterial Safety

MARSHFIELD — Protecting the safety of our drinking water is important, and difficult, because of the fractured geology and cave structure underlying the Ozarks, according to Bob Schultheis, a natural resource engineering specialist with University of Missouri Extension.

“Missouri Department of Health and Senior Services testing results show that, depending on the county, one-third to one-half of private water well systems in southern Missouri are contaminated with coliform bacteria at unsafe levels,” said Schultheis.

What are some common ways water wells can get contaminated?

Failing septic systems located near the well would be the biggest concern, especially if the well was drilled before 1987, when there were no construction standards. Heavy rainfall flushing bacteria down sinkholes and losing streams is a concern, as is new housing development within a couple of miles of the well. Opening a plumbing system to make repairs is another common path for contamination.

“Some people tell me they have never had their water tested, and don’t want to, for fear of what they might find. Others say they have never gotten sick, so the water must be OK. But when their grandkids come to visit and get sick after drinking the water, then they get concerned,” said Schultheis. “Former city dwellers moving to the rural Ozarks know it’s important to test the water because it was routinely tested for them in the city, but they aren’t sure how to go about it themselves.”

So how often should a private water well be tested for bacteria and what does it cost?

The water should be tested at least annually, preferably quarterly. Sample bottles with instructions can be obtained from the county health department (health.mo.gov/living/lpha/ lphas.php), and the testing typically costs $10.

For the most accurate results, keep the sample cool and away from light and get it to the lab within six hours of drawing it. Test results are returned within a week and should be kept with your important papers for liability purposes. The lab will test for both total coliform and E.coli bacteria, and the water will be rated “unsatisfactory” if either type is found.

“If your well tests positive for bacteria, shock-chlorination with ordinary, unscented laundry bleach or swimming pool chlorine tablets is often an inexpensive and effective way to correct the problem. Shock chlorination kills disease-causing organisms and controls nuisance problems, such as iron bacteria (orange staining) and hydrogen sulfide (rotten egg odor),” said Schultheis.

More detailed information on bacteria in water is available at extension. missouri.edu/p/WQ102 and on water protection at extension.missouri.edu/ webster/water.aspx.

If you have questions on this topic or other engineering concerns, contact Schultheis at the Webster County Extension Center in Marshfield by phone at 417-859-2044, by email at schultheisr@ missouri.edu.