by Glen Arnold, Putnam County
The transmission of disease through drinking water is an important concern. That’s why OSU Extension recommends that private wells be tested annually for total coliform bacteria. Many years ago before scientists understood disease transmission, human illnesses such as typhoid, dysentery, cholera, hepatitis, and giardiasis were transmitted through drinking water contaminated by waste when outhouses or animals were located next to hand dug wells.
Coliform bacteria are common in the digestive systems of humans, pets and livestock. They are also found in the soil and in decaying plant material. While they do not cause disease, their presence in a water test is cause for concern as it could indicate a more serious kind of contamination. Iron bacteria that can form a reddish-brown slime that coats the inside of water pipes is not a health concern but can also cause a total coliform bacteria test to be positive. Almost any repairs made to a water well that involves pulling the pump or water lines can also cause the water to test positive for coliform bacteria.
Your local health department should be contacted to conduct a total coliform bacteria test. It costs about $35.00. They have the sterile containers and know the proper procedure for taking water samples. The results will either be positive or negative. If a positive test result occurs, additional testing is usually done to determine whether the bacteria present is from soil, decaying plant material, or fecal bacteria such as e-coli from human or animal waste. Studies have shown that about one in four water wells will test positive for coliform bacteria. About seven out of ten springs and cisterns will also test positive.
When a water well tests positive for total coliform bacteria it usually possible to solve the problem through a process called shock chlorination. This involves pouring the correct amount of laundry bleach into the well and then allowing it to kill the bacteria both in the well and the water lines. Your local health department or Extension office has a handout on this procedure which has recommendations on the proper amount of bleach to use. A few days later the well can be tested for coliform bacteria again to be certain the chlorination worked.
The best way to maintain a safe well water supply is to prevent contamination. Be sure your well casing is in good shape (no cracks or rust) and extends about a foot above the ground so surface water cannot enter the well. Also be sure the cap fits tightly so rodents cannot fall in or kids can’t pour anything down the well. Our subsoils can do a terrific job of protecting our drinking water so long as we make the surface water infiltrate the ground to recharge the ground water feeding the wells.
When septic systems do not function properly human fecal coliform bacteria can be found in drainage ditches or can infiltrate an improperly protected water well. This is why it’s recommended that private wells be located at least 50 feet from any septic system. It’s also recommended not to apply livestock manure within 50 feet of a well or have fuel storage tanks within 100 feet of a well.