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How to Kill E.Coli in Drinking Water

Updated February 21, 2019

Escherichia coli, better known as E. coli, is a diverse group of bacteria. Some E. coli strains can cause human illnesses including diarrhoea, urinary tract infection, respiratory illness and pneumonia. There are a few effective ways to kill E. coli in your drinking water, according to the Centers for Disease Control and Prevention. These include boiling and using chemicals. You can also use filtering systems to remove E. coli from drinking water, but these methods do not kill the bacteria.

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  1. Pour the desired amount of water to a pot. You can use water from tap, streams, rivers and lakes. If taking water from natural sources, scoop the water from the surface so you will not disturb the bottom material and mix it in with the water. Do not use cloudy or turbid water.

  2. Start your heat source. You can use a wood fire, gas stove / grill or a hotplate for boiling water. If you are using an open flame, such as by burning wood, make sure the pot you are using is suitable for that type of use.

  3. Place the pot with the water to the heat source. Wait until the water begins to boil. According to the Centers for Disease Control and Prevention, bringing water to rolling boil for one minute is very effective in killing E. coli.

  4. Turn off the heat source and let the water cool down before drinking it. The time it takes to cool down the water will depend on the amount of water and from the surrounding environmental temperature. You can fasten the cooling by placing the pot in cold water. Cover the pot so you will not recontaminate the water.

  5. Pour the desired amount of water to a bottle. You can use tap water or water from natural sources like streams, lakes and rivers. Do not use turbid or cloudy water.

  6. Add the iodine tablets to the water using a ratio described in the label or other instructions. For example, use two Potable Agua iodine tablets for one quart or litre of water. Do not cap the bottle to allow slight leakage of air.

  7. Wait five minutes if using Potable Aqua tablets, or as long as advised on the label or instructions.

  8. Shake the bottle so that you allow water to rinse the bottle neck and screw threads. It is all right if little water seeps out while you do this. This step will help disinfect the parts of bottle that might contain untreated water.

  9. Close the cap and wait 30 minutes, or a time described in the label, before drinking the water. Dissolved iodine will kill the E. coli by penetrating the cell wall and inactivating the bacteria.

  10. Tip

    You should boil water for at least three minutes if you are above 6,562 feet or 2,000 meters. The instructions for treating water with iodine tablets can change depending on the manufacturer. Always follow the manufacturer's instructions.


    Water treated with iodine is not recommended to pregnant women, people with thyroid problems, people with iodine hypersensitivity and for continuous use for more than few weeks at a time. Always consult your physician before using iodine tablets to treat your water. Boiling water is hot and can cause burns. Always be careful when handling boiling water. There can be several other microbes and parasites in water besides E. coli. Boiling is very effective killing many different microbes and parasites, according to the Centers for Disease Control and Prevention, while iodine tablets may not be.

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Things You'll Need

  • Water
  • Pot
  • Heat source
  • Bottle
  • Iodine tablets

About the Author

Maria Parepalo began writing professionally in 2006 and has published in medical journals as well as online. She graduated with a bachelor’s degree in laboratory sciences from Helsinki Polytechnic in 2002 and is currently working on her doctoral degree in cell and molecular biology.

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