What's on Tap: E. Coli in Drinking Water


Defined by the Center for Disease Control, "Escherichia coli (E. coli) are bacteria found in the environment, foods, and intestines of people and animals." Part of a large, diverse group of bacteria, e. Coli live in the intestines of humans and animals. Some kinds of e. Coli are harmless and play an important role in the digestive system. Other kinds can be the cause of illnesses like diarrhea, urinary tract infections, respiratory illness and pneumonia. The diarrhea-causing strain of E. coli can be transmitted through contaminated water or food, or through contact with animals or persons.


E. Coli is naturally present in the environment but its presence in drinking water usually signals recent sewage or animal waste contamination. The microorganisms make their way into water sources when rain and snow washes it into rivers, streams, lakes, or ground water, and into the source of drinking water. When the water source is not treated or is inadequately treated, E. coli may end up in drinking water.


The Mayo Clinic says signs and symptoms of E. coli infection typically begin three or four days after exposure to the bacteria, but in some cases, symptoms can be experienced one day after or more than a week later. The infections can range from very mild to severe or even life threatening. Signs and symptoms include:

  • Diarrhea, which may range from mild and watery to severe and bloody
  • Abdominal cramping, pain or tenderness
  • Nausea and vomiting, in some people
  • A low-grade fever (less than 101 degrees) may occur

There is no medicine or treatment for e. Coli. The Mayo Clinic recommends avoiding anti-diarrheal medication and antibiotics because they can complicate cause complications and slow the recovery time. It's recommended to rest and get plenty of fluids during the period of infection, which usually lasts 5 to 7 days.


If your water is supplied by the city, it is being routinely tested for contaminants like e. coli to be sure it's safe for use. Should the water supply exceed the maximum contaminant level, the supplier is required by law to report unsafe levels to customers. Well-water users need to routinely test their water supply to be sure it's safe for consumption. Because well water is easily impacted storms and farmland run off, the EPA recommends well water be checked yearly. You can test the water yourself using an at-home kit designed specifically for well water, or hire an independent lab to test it for you. If you're still concerned about the quality of the water in your home, there are a few ways to learn about its safety:

  1. Test the water yourself. Using an at-home kit for city or well water, take a water sample and then mail it to a lab for analysis. Some of these test kits will include a recommend a filtration solution best suited to your environment in addition to the lab report. An important note: Not all test kits are the same. Make sure the kit you purchase will test for the contaminants you are concerned about.
  2. Request a water quality report. All public water systems in the U.S. are required to provide customers with an annual Consumer Confidence Report that details the water quality in your community, just ask for a copy.
  3. Call the EPA's Safe Drinking Water Hotline for more information about drinking water safety in your area: 1-800-426-4791.


Five percent is the maximum permissible level of e. Coli in water that's delivered by a public water system.


There are two ways to treat water to prevent e. Coli infection: boiling water or treating it with an ultraviolet light. Because boiling water is time consuming and inconvenient, a ultra-violet water filtration system is a more efficient way to kill or inactivate e. Coli. In addition to being the only filter that will kill microorganisms, UV filters are chemical free, cost effective and environmentally friendly. If your water is sourced from a well, it's important to perform yearly well water treatments in addition to using a water filtration system.


When it comes to selecting a UV filtration system to clean e. coli and other harmful bacteria from your drinking water, the choices range from pocket-size perfect for camping to whole-home that clean every drop of water that comes into your home. These three systems are top performers:





Regular replacement of the filter and/or cartridge is critical to maintaining their effectiveness and reducing bacterial contamination. An overused or out-of-date filter can become dangerous because the filter will no longer trap contaminants, allowing them to leach back into your water. For the safety of you and your loved ones, it's important not to put off replacement too long. There are four effective ways of knowing when it's time to replace your water filter:

  1. Follow the manufacturer's recommendations. Their specified replacement timing will err on the side of caution so you can be assured that your water quality will always be safe.
  2. Measure usage. Install a filter measurement meter or filter monitor that connects to the incoming water line that feeds the filter system and measures the number of gallons that pass through. Then using the manufacturer's recommended usage limit, program the monitor to alert you when you've reached the allowed number of gallons. You'll know exactly when it's time to replace the filter.
  3. Read your water bill. If your home is supplied with municipal water, your water bill will tell you exactly how much water is used monthly. Compare your actual usage to the manufacturer's recommendation and plan the replacement accordingly.
  4. Monitor manually. If you have non-municipal water, the most cost effective method is to monitor your filter manually either with your palate or a water testing kit. Start with routine water tests that look for lead, microorganisms and other contaminants to verify whether your filters are still removing them. For drinking water systems, simply fill a glass with water and check the flavor yourself. You'll be able to see or taste when the filter is exhausted and no longer purifying your water because the water flavor will be unpleasant.


For answers to e.coli-related questions, recommendations on the best filter for your home or general drinking water questions, contact us.