Contamination with this scary-sounding bacteria is actually a common problem in American wells. Not all coliform bacteria will make you sick but yes, some types are distinctly dangerous. Therefore, it’s important to know if there are coliform bacteria in your well, what type it is and how to eliminate it. The steps to take are actually pretty simple.
Which Types of Coliform Bacteria Are Dangerous?
Despite the bad reputation of coliform bacteria, only a small number of the thousands of different strains are harmful. The term “coliform” is a general descriptor for this rod-shaped bacteria found in soils, surface water, and vegetation. These bacteria are abundant in nature.
One group of bacteria in this category is called “fecal coliform” which indicates that this bacteria had its origins in the digestive tract of an animal or human. The presence of fecal coliform bacteria in a water supply is a clue that the water source has been contaminated by some kind of fecal waste. There is a greater risk that this water will make those consuming it sick which means that the source of the water contamination needs to be found and eliminated after the well is disinfected.
You have probably heard of “E. coli.” Maybe you read about vegetables being recalled because of E. coli contamination. Again, this term refers to a group of bacteria strains. Not all are pathogenic (disease-causing). However, some strains of bacteria in this group can cause serious illness. Here too, there are hundreds of different strains. Six E. coli strains are well-known for their ability to cause illness. One of them, E. coli 0157:H7, produces a potent toxin that breaks down the lining of the intestinal tract. The result is bloody diarrhea. There are 70,000 cases of this type of E. coli infection each year.
For Safety, Public Warnings Are Needed About E. Coli Outbreaks
Outbreaks of E. coli contamination make their way into the headlines so the public can be warned to dispose of or return contaminated foodstuffs to the stores where they were purchased. For example, in one situation reported by the Centers for Disease Control and Prevention, walnuts in California and Oregon were found to be contaminated with E. coli. Seven people were hospitalized, but there were no deaths in this instance.
After a hurricane or flood, personal water wells are much more likely to be contaminated with E. coli. After two hurricanes passed through North Carolina, nearly half the well water samples received by the North Carolina Department of Health and Human Services tested positive for E. coli. This is not surprising, given the vast number of hogs housed in this state. It’s vital to follow well water testing and disinfection protocols after major storms or flooding.
States may provide warnings about potential contamination with E. coli but, after that, any action is completely up to the well owner.
Prompt Identification of Coliform Bacteria in Wells is Essential
As noted, the presence of any coliform bacteria is a warning that the well or water source may be contaminated with human or animal fecal matter. Simply testing water for the total number of coliform bacteria and the presence of E. coli bacteria is fast and inexpensive. The total count of coliform bacteria will inform you about the relative sanitation of your water. If you have any E. coli (fecal) bacteria, you’ll know you need to look further for a source of animal or human contamination.
The following sources can introduce E. coli bacteria into your well:
- Surface water runoff. In times of flood or if the wellhead is too close to the ground, surface water can carry fecal matter into the well from feedlots, dog runs and pastures.
- Malfunctioning septic systems. Poorly maintained septic systems can leak fecal coliform bacteria which then makes its way into the well.
- Abandoned septic systems and wells. If old, abandoned wells or septic systems are not properly sealed, the old toxins and bacteria from these systems can make their way into the current supply of well water.
- Damaged wells. Broken casings or casings that are too short can permit surface water to enter the well.
- Poorly constructed wells. The well must have been properly sealed with grout when it was built. If this is not done, it may or may not be possible to repair it, depending on the size of the casing.
- Repairs or service. When repairs or any kind of well service are done, it is possible that coliform bacteria contamination can be introduced to the well and its water.
- Contamination from nearby bodies of water. A shallow or hand-dug well can be contaminated by nearby lakes, ponds or streams.
Your first step is, of course, testing your well water to determine its bacterial count. According to the Environmental Protection Agency, the maximum level of bacteria in well water is zero total coliform colonies per 100 milliliters of water. (One hundred milliliters equals about 3.4 ounces.) A properly built well in good repair should be able to achieve this benchmark. If you find any coliform bacteria in your well, further steps to eliminate it are advised.
How to Disinfect Well Water When Coliform Bacteria Are Present
There are two ways to disinfect a well. One is with chlorination and the other is to install a continuous disinfection system. The right solution for any well depends on the reason the well is currently contaminated.
If, for example, a well was contaminated by being serviced or if flood waters added coliform bacteria to the well, a single decontamination procedure may be all that is needed. That well is not likely to become contaminated again in the near future. However, if the well is going to be subjected to continuous contamination, then a continuous disinfection system will be needed. This might be the solution needed if an agricultural activity starts up in the vicinity of the well and contamination is traced to this source.
You may read that all you need to disinfect your well is household chlorine bleach. This is not recommended for disinfection of personal water wells. Chlorine bleach used for laundry and other uses is heavier than water. It can become trapped in pockets in your plumbing system. A well owner may have to run thousands of gallons of water through their plumbing system after shocking the well to eliminate the smell of bleach. No one wants to serve their family drinking water that smells like bleach.
A better solution is the use of calcium hypochlorite which does its job and then is easily flushed from the system. Calcium hypochlorite is approved by the Food and Drug Administration for the disinfection of private water wells.
Choosing a Continuous Disinfection System for Your Well
Some states require wells to have a continuous disinfection system for any well that is subject to repeated contamination. There are several choices for a homeowner who needs to constantly disinfect their well water.
- Chlorine. Automated systems that add small amounts of chlorine to well water are available. A chlorine pump injects the chemical into the water automatically as the well’s pump draws in new water. Chlorine can react with organic material in the water, such as plant matter, so a filter to remove this matter before it is chlorinated must also be added. The interaction of organic materials and a chlorine bleach generates new, toxic substances referred to as trihalomethanes which you don’t want in your drinking water.
- Ultraviolet. Running the water past an ultraviolet light disrupts the DNA of any microorganisms so they can’t reproduce.
- Chlorine dioxide. This gas will not react with plant matter like chlorine will. Also, chlorine dioxide is effective against bacteria, viruses and protozoa. It will work at lower concentrations than chlorine and remain effective longer. It has no taste or odor. However, it can be corrosive to plumbing elements.
- Ozone. Bubble diffusers send ozone bubbling through water. Ozone is capable of killing bacteria, viruses and parasites. But ozone, like chlorine dioxide, can be corrosive. The gases must also be vented to the outside after the water is disinfected.
- Iodine. Older iodine systems may still exist. However, some individuals are sensitive to iodine and the sale of iodine has been limited because of its use in making illegal drugs. So these systems are being replaced by chlorine or UV systems in most areas.
Steps to Follow to Detect and Eliminate Coliform Bacteria in Your Well Water
The initial step is, naturally, getting the water tested. If it tests positive for coliform bacteria, the household should stop using the water for drinking or cooking. Lay in a supply of bottled water or follow the steps recommended to disinfect water before using. Most communities with municipal water contamination problems recommend boiling water for at least one minute at a full rolling boil.
Once the household has safe water to use, then address the problem with the well.
- Retest your water. Confirm the contamination. Follow water sample collection instructions precisely to ensure there is no contamination of the sample.
- Disinfect your well. Chlorination will do it, but use calcium hypochlorite instead of household bleach. This will eliminate the bacteria in the well at the moment. Follow the instructions that come with the disinfection kit. Before using the well water, retest to ensure bacteria have been eliminated, following the instructions accompanying the test.
- Inspect the well and surroundings. You are looking for the source of contamination. As noted above, you are looking for abandoned wells or septic systems, animal or human sources of fecal contamination, or a faulty wellhead. It’s also possible that recent landscaping could now send water flooding toward the wellhead. If there is no obvious environmental source, get a professional well service company out to inspect the well for damage.
- Repair the well. This could require fixing a broken casing, replacing a defective well cap, raising the level of the well cap or even digging a new well if all else fails. It is also possible that the aquifer itself may be at fault, being made of fractured or coarse material that does not filter contaminants. In this case, adding a continuous disinfection system would be the only way to repair the well.
Remember to Test and Disinfect Annually as a Smart Maintenance Action
There are two ways that you may discover that your well is contaminated with coliform bacteria. First, you may do an annual test, which is recommended by most public health services. The second way you may find out is if members of your household suffer symptoms like upset stomach, diarrhea, vomiting or fever.
These signs of coliform infection can be particularly dangerous for babies, the elderly or anyone who is immunocompromised. This last category would include anyone who is being treated for cancer or who has received an organ transplant. It is far better to detect coliform contamination through a routine test than through the illness of a loved one.
The best time to test is when your well water is most likely to be unsafe, usually following a heavy rainy season or during the warmer months. Do another water test if there is a change in the color, taste or odor of your water.
ETR Laboratories Helps Thousands of Well Owners Keep Wells Healthy and Pure
Every month, ETR Laboratories runs tests for well owners all over the country to help them detect troublesome or dangerous contaminants. We can provide tests for Total Coliform, Fecal E. Coli and Total Bacteria Count. Advanced testing can even identify the species of bacteria present, when this is needed.
Our disinfection kit contains the safer and FDA-approved disinfectant calcium hypochlorite as well as a follow-up test at no additional charge to confirm that the water has been fully disinfected. To choose the right test for your situation, please visit our Water Tests page to make your choice. To purchase a well disinfection kit, please visit this page.
We look forward to helping you keep your well water safe and pure.