Coliform Bacteria in Well Water

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If you drink from a private well water source, you’re probably at least somewhat familiar with coliform bacteria. Commonly found in soil and plants, most coliform bacteria are usually harmless. But the presence of coliform bacteria is usually an indication that your well water also contains disease-causing bacteria from animal waste or septic systems.

πŸ€” What Are Coliform Bacteria?

There are hundreds of types of coliform bacteria, and most are relatively harmless. The majority of coliform bacteria occur in soil and plants, and some even live on surfaces in our homes. Coliform bacteria also occur harmlessly in human or animal digestive tracts.

There are three types of harmful coliform: total coliform bacteria, fecal coliform and E. Coli coliform. Total coliform live in soil and animal waste, while fecal coliform is present in the feces of animals. E. Coli is one of the most common species of fecal coliform, and, being the least likely to live in the natural environment, is the best indicator for fecal coliform.

It’s likely that if total coliform bacteria have made their way into your drinking water, disease-causing coliform, like E.Coli, are also present.

🩺 Health Risks from Coliform Bacteria

The majority of coliform bacteria don’t pose any health risks and won’t cause disease. They don’t have any taste or odor, so you won’t even know they’re there. But if disease-causing coliform makes its way into our drinking water, we may experience symptoms including:

  • Fever
  • Diarrhea
  • Stomach cramps
  • Nausea
  • Vomiting
  • Fatigue
  • Headaches

Aside from the obvious symptoms of illness, coliform bacteria may also affect the health of humans in the following ways:

  • May result in UTIs – When bacteria such as E. Coli get into the human urinary tract, it can result in a urinary tract infection. This kind of infection can cause pain in the pelvis and difficulty urinating. In serious cases, UTIs can spread to the kidneys, requiring treatment by a health professional, and can sometimes result in hospitalization.
  • Can cause typhoid – By this year, the majority of members of the public have been vaccinated against typhoid. But if you haven’t had a typhoid vaccination, it may not be safe for you to drink water containing certain bacteria that may risk you contracting the disease. Typhoid can be incredibly serious, and usually, it must require hospital treatment. It can cause rash, fever, headache and severe stomach pains.
  • Can cause gastrointestinal infection – If you experience health effects such as vomiting and diarrhea after drinking from a well water system, you may have a bacteria-induced GI infection. Luckily, this sort of infection can be treated with antibiotics, but it still isn’t pleasant to experience.

Not all members of your household will respond to the presence of these bacteria in the same manner. It’s common for children and the elderly to experience more serious symptoms and even life-threatening health effects compared to the average adult. Either way, no matter what your age, it’s better not to risk ingesting bacteria from your water source, as you never know how it could harm your health.

🦠 How Do Coliforms Get Into Well Water?

Coliforms typically enter wells naturally through surface water runoff. If your well isn’t properly sealed, rainwater could wash these bacteria through the surrounding soil and into your well.

I’ve highlighted some of the routes that coliform could take to get into your well source below.

  1. Through the top of the well, such as the well cap or the well pipe
  2. Through the well pipe, if the grout seal isn’t effective enough
  3. Through storage tanks, well casing, pump and pipes that aren’t watertight

Coliform bacteria may also occur in wells after work has been carried out that wasn’t followed by adequate disinfection. Finally, you might not have a flaw with your well’s design itself, but shallow wells located near to a body of water may draw this water from the surface. The same goes for if wells are located near an area of groundwater prone to animals’ waste (such as an agricultural site), sewage or septic systems.


πŸ§ͺ How to Test for Coliform Bacteria?

The Environmental Protection Agency recommends that you test for contamination of well supplies on a once-yearly basis. There are several ways to test for bacteria in your wells and drinking water, but I’ll be focusing on two of the easiest and most accessible methods for the majority of homeowners.

Private Laboratory Testing

If you have any reason to be concerned about bacterial contamination in your well, you may want to consider water testing by a laboratory. This is an especially good idea if you’ve moved into a property with a private well and you want to carry out well water testing to ensure it is safe to use, or you’d like to use an old well and you’re keen to make sure it still operates well.

Private laboratory water testing is one of the most thorough testing options for wells, and will tell you exactly what levels of bacterial contamination you’re dealing with. Laboratories don’t have to solely test for total coliform bacteria in wells, either – they’ll usually be able to give you a broad spectrum of which contaminants are found in your drinking water supply, and assess your overall water quality. Keep in mind, though, that if you opt for the “test for everything” approach, you’ll rack up a bill of hundreds of dollars for your test results.

completed tap score water test

If you just need information about the potential presence of coliform in well water systems, you can ask for an E.coli or Escherichia Coli test (remembering that this coliform group is the most effective indicator of bacteria-contaminated water in wells). These tests may cost as little as $30, but could also cost above $100, depending on which laboratory you go with.

I recommend checking out Tap Score, hands down the best certified lab for water testing.

water testing with tap score

A laboratory will require a water sample in a clean bottle from your well. This sample will be tested, and whatever is found will be reported back to you, usually via email and/or over the phone. If your water test came back positive for coliform, don’t panic – I offer guidance on the best water treatment for coliform in wells at the bottom of this guide.

Well Water Testing Kit

You can carry out well testing for E.coli bacteria yourself – there are plenty of single-use testing kits for wells and public water sources available online. Some testing kits may test solely for E.coli, while others test for a broader range of contaminants. If your ultimate goal is to look for coliform bacteria, make sure your test kit tests for the presence of this contaminant in particular.

To use a water testing kit, collect a sample of drinking water in a clean bottle or container. Dip the provided test strip into the water sample, holding it for a number of seconds (usually between 2 and 5). Next, remove the strip from the sample and let it sit on an uncontaminated surface for the recommended amount of time (usually 1 to 2 minutes). The strip will take on a color to indicate your water sanitary quality – i.e. the contaminants your well contains – and you can compare the strip to the included color chart to see what you’re dealing with.

The obvious advantage of a well water systems test kit is that you’ll get immediate positive or negative results from your sample, and test kits tend to be a lot more affordable at $20 to $50. The setback, however, is that while a test kit may be able to indicate that bacteria are present in well sources, it won’t tell you the levels of contamination or which types of bacteria are present.

Remember that many types of bacteria are harmless, but types like E.coli can make you sick. If you can, look for a test that specifically detects E.coli, as this is the contaminant you need to be most aware of in your water supply for your safety.

πŸ”Ž How to get Rid of Coliform Bacteria in Well Water?

If you’re thinking, “my well water tested positive for coliform. What next?” I’ve got you covered.

Learning that your well contains coliform bacteria is hardly happy news. But you don’t have to spend the rest of your life drinking bottled water, nor do you have to build a new, coliform-proof well.

First off, before you consider solutions for removing bacteria from your well water system, you need to eliminate the cause of this contamination when possible. It’s important that you know how this harmful contaminant has made it into your groundwater, and whether there’s any way to prevent it from getting into your well.

You may need to make small modifications or repairs to your well casing or pipes to prevent the leaching of bacteria. When modifications aren’t possible, it may be a better option to remove bacteria from your water before it reaches your home.

If you’re looking for a simple, long-term strategy for coliform removal, you have a number of options:

UV Light

UV purification is one of the most effective means of eliminating coliform bacteria from your drinking water. This type of water treatment is capable of targeting not only bacteria, but also protozoa and viruses, making water safe to drink.

A UV system is typically installed at water’s point of entry into your home. Because this system is installed at your main water pipe, water will have to travel through the UV system before it can get any further into your property.

When water passes through the UV chamber, the lamp will emit intense UV light. These rays penetrate pathogens like bacteria and alter their DNA, making them unable to reproduce or cause harm. While UV treatment doesn’t remove bacteria from your drinking water, it prevents bacteria contamination from being able to cause disease or sickness in people who consume your water.

UV systems typically cost between $50 and $130 for point of use on their own. They use very little electricity per year and require limited maintenance – you’ll be required to change the UV lamp once a year and clean the sleeve every three months or so.

Many people choose to install a UV light at the end of a whole home water filtration system to tackle the broadest range of contaminants. UV can only kill living pathogens, while whole home water filters can also remove common contaminants like dissolved minerals, agricultural chemicals like fertilizers, volatile organic compounds and heavy metals that might be in your surface water source.

UV Ultraviolet disinfection process


Chlorination is a common and cost-effective form of disinfection that’s used in most US states to remove common contaminants from city water. It involves using a pump to add a measured amount of chlorine to water, which breaks the chemical bonds of bacteria and other pathogens like viruses and protozoa. On a small scale, you can disinfect contaminated well water yourself using a chlorine injection system.

In a well chlorine injection system, chlorine is added to well water, usually via a pump, before it travels through the pipes into your home. Typically, a chlorine injection system will perform disinfection and hold chlorinated water supplies from your well in a clean tank until you need to use it in your home. This gives water plenty of contact time with the chlorine, which is more effective than introducing chlorine to your water source while it’s already on the move.

When you switch on a faucet or activate a water-based appliance, the chlorinated water will make its way into your house, as it usually would.

Chlorine injection water systems can cost hundreds of dollars – usually between $500 and $800. While these systems are a big investment, they’re usually pretty cheap to maintain in the long run, and just require topping up with chlorine as advised in the user manual (which should cost around $50 per year). This solution is often partnered with a carbon filter after it to remove the chemical before it enters the home.

Related: How long does it take for water to clear after shocking a well?

🚰 Which Solution is For Me?

It depends on a number of factors, including your budget, the level of contamination you’re dealing with, and which of the systems appeal to you the most.

You might not like the idea of chlorinating your contaminated water; in which case, UV is a better option. But if you have a bigger budget, chlorine injection systems could be the better long-term option. Both systems work well to remove bacteria from water, but make sure you’re fully aware of your contamination issues before making an investment in either solution.

❔ Frequently Asked Questions

Are there any easier ways to remove bacteria from well water?

I’ve covered how to treat coliform bacteria in well water in this guide. There are a few other methods that can remove bacteria from water, such as boiling. I recommend boiling your water if you have no other option, as boiling will kill pathogens and ensure water is safe for drinking. But it’s not the best long-term solution as you’ll need to frequently boil each batch of water before you can drink it.

How often should I test for bacteria in wells?

The EPA recommends testing for bacteria once per year for your safety. If your well is located near septic sources or a farm, you must test regularly in case of ground water pollution.

I need more advice – where can I get it?

Your local Department of Health may advise on possible state contaminants on their website. You could also contact your Department of Health with questions about your specific location and how it may affect your ground water quality. Aside from your Department of Health, the CDC provides some good information, too – here’s a useful link.

  • Jennifer Byrd
    Water Treatment Specialist

    For 20+ years, Jennifer has championed clean water. From navigating operations to leading sales, she's tackled diverse industry challenges. Now, at Redbird Water, she crafts personalized solutions for homes, businesses, and factories. A past Chamber President and industry advocate, Jennifer leverages her expertise in cutting-edge filtration and custom design to transform water concerns into crystal-clear solutions.

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