Escherichia coli (E. coli), fecal coliforms or enterococci

The presence of Escherichia coli (E. coli), fecal coliforms or enterococci in water indicates that it has been contaminated with stool. Such water can contain microbes (bacteria, viruses or parasites) that cause health problems. To be safe, drinking water should not contain any of these micro-organisms.

Health risks

Water contaminated with micro-organisms can cause gastroenteritis, symptoms of which include the following:

  • Diarrhea
  • Abdominal cramps
  • Nausea
  • Vomiting

Protection and prevention

You should conduct a microbiological analysis of your well water at least twice a year:

  • In the spring, when the snow melts
  • In the fall, during heavy rains

In addition, have your water tested:

  • If you notice a change in taste, smell or appearance
  • When work is done on or near the well

If your water is contaminated with micro-organisms, bring it to a rolling boil for at least one minute before drinking it, or use bottled water to:

  • Drink
  • Prepare beverages
  • Prepare baby formula and food 
  • Wash fruits and vegetables to be eaten raw
  • Make ice
  • Brush your teeth and rinse your mouth

You can use tap water without boiling it to:

  • Wash dishes with hot water
  • Wash clothes
  • Wash your hands with soap and water
  • Take a shower or a bath

Make sure that babies and young children do not swallow water when taking a bath. You can also bathe them with a washcloth.

To decontaminate the water, you must determine the cause of the contamination and take corrective measures. Make sure that your well and septic systems are built according to standards. Continue boiling water until test results confirm that it is safe. If fecal contamination persists in your water, you can install a residential water treatment system to get rid of the micro-organisms. Be sure to install a certified system that conforms to NSF/ANSI standards and follow the manufacturer’s maintenance recommendations. If you install a residential water treatment system to disinfect your water, you must verify its effectiveness by testing your water twice a year (in the spring and fall).

Last update: August 22, 2016


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