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Well Water

Is your well water safe to drink?

Testing your well water  at least 3 times every year will keep you up-to-date on the quality of your family's drinking water. It is your responsibility as a well owner to take samples, and inspect your well to ensure that your drinking water is safe. You can order a well water sample bottle for bacterial analysis from the Health Department's website.

Who relies on private water supplies?

  • Many Halton Region residents, living primarily in rural areas, rely on private wells, cisterns or other sources for their drinking water.
  • Municipal water supplies in cities and towns are maintained and tested by Halton Region's Planning and Public Works department. However, private wells in rural areas are the responsibility of the homeowner.

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What happens if I drink contaminated water?

  • Private wells can become contaminated with bacteria, nitrate, or other chemicals.
  • The effects of drinking contaminated water can range from no reaction to severe illness or even death.
  • Many factors affect the possible reaction such as the age and general health of the person, the type of contaminant, the amount, and how long the person was exposed to the contaminant.
  • Some of the effects of drinking contaminated water may happen right away, or may not be noticed for many years.

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What types of contaminants could get into my well water?


  • When a water test shows the presence of bacteria, it is considered unsafe to drink until the problem is fixed and the well is disinfected. The bacteria may pose a health risk. An alternate drinking water supply should be used.
  • Well water may be brought to a rapid boil and boiled for one minute to make it safe for drinking. Allow it to cool, and then refrigerate in a clean container.
  • Coliform organisms are a group of bacteria that are commonly found in the environment, and are an indicator of the safety of your water. Coliform bacteria are not harmful, but their presence tells you that other disease-causing organisms may be in your water supply. The presence of more than five coliform bacteria in a water sample usually means that surface water has washed contaminants into the well.
  • E. coli bacteria live in the intestines of humans and warm blooded animals. If any amount of E. coli bacteria is found in a water sample, human sewage or animal faeces has contaminated the water supply.



  • Arsenic is an element that can occur naturally in well water if soil or rocks that contain arsenic are present in the area. Less commonly, arsenic may be in well water as a result of human activities such as mining or agriculture.
  • Ingesting water that contains elevated levels of arsenic over a long period of time may increase the risk of lung, skin, bladder and other cancers.
  • Private well owners living near locations where arsenic has been found at elevated levels in groundwater should consider testing their well water for arsenic.
  • More information on arsenic in groundwater is available in the Health Department’s Arsenic in Well Water fact sheet.

Herbicides and Pesticides

  • Herbicides and Pesticides from both agricultural and household use can contaminate wells if used improperly or excessively. Always read and use the amount stated on the manufacturer's label.


  • The presence of nitrate in your well water is usually the result of farming activities like fertilizing or seepage from septic systems. At levels above 10 milligrams per litre of water, nitrates can interfere with an infant's blood ability to carry oxygen and could cause a condition know as "blue baby syndrome". The medical term is methaemoglobinaemia.


  • Sodium is an essential nutrient found in many foods and water. Livestock farming, releases from sewage systems, and human activities, such as the storage and use of road salt and fertilizers, can also increase sodium levels in groundwater. 
  • Sodium may also be present naturally in groundwater as a result of salt deposits and weathering of rocks. Sodium levels in groundwater vary across Halton.
  • Drinking water can become a significant source of sodium for some people who have health conditions that may require them to be on a sodium-restricted diet.
  • Additional information is available in the Halton Region Health Department’s Sodium in Well Water fact sheet.

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How can I test my well water to find out if it is safe?

  • Refer to Testing Your Well Water Supplies.
  • Follow the instructions closely or your results may not be accurate.
  • The Ontario Ministry of Health and Long-term care Public Health Lab will test well water samples for bacteria (total coliforms and E.coli) free of charge.
  • Test your well water at least three times a year for bacteria (spring and fall, and one other time).
  • Other Tests - The Health Department will test water for nitrates free of charge. Please contact the Health Department to arrange for a nitrate test.
  • Although the Health Department does not offer testing for substances other than bacteria or nitrate, public health inspectors will be pleased to advise you about other tests that may be done in relation to a specific health issue.

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How can I maintain my well to prevent contamination?

Well Location

  • Make sure the well is located at a safe distance from any source of contamination such as septic systems, barnyards and roads.
  • A dug well should be at least 30 metres away from a septic system and a drilled well should be at least 15 meters away.
  • The land around a well should slope away from the well to prevent surface water from flowing to the well casing.
  • Do not store, use or dispose of garbage, manure, petroleum, salt, pesticides or any other potential contaminant near the well.

Well Construction

  • The sanitary well seal and the cap should be securely in place and watertight. If the cap is damaged or cracked, replace it right away.
  • The sanitary well seal could be a minimum of 40 centimetres above ground level. The connection at the well casing for pump and electrical lines should be watertight and properly sealed.
  • Well vent pipes should have screens to prevent anything from getting into the well.

How to Protect Your Water Supply

  • Stop liquids, waste material, garbage, or manure piles from draining towards the well.
  • Do not treat the area around the well with pesticides or fertilizer.
  • Do not flush oils, detergents, paints, solvents or other chemicals down the toilet or sink.
  • Chlorinate and flush your water supply systems after any repairs. Call the Health Department for a copy of the instructions on how to chlorinate your well.
  • Always dispose of household hazardous wastes via the Region's Household Hazardous Waste Program. Remember, waste poured into the ground can eventually get into your water supply or your neighbour's.

Tips to Save Water

  • Stop the leaks! A leak of one drip per second wastes 10,000 litres of water in one year.
  • Don't use your toilet as a garbage can.
  • Replace your toilet with an ultra low-flush toilet to greatly reduce household water consumption.
  • Install low-flow showerheads.
  • Avoid using garbage grinders as they greatly increase water use.
  • Only run your dishwasher when it is full.
  • Wash only full loads of laundry, but avoid overloading the machine.
  • If you machine has a "suds-saver" feature, be sure to use it.
  • Only water your lawn once a week. Your lawn only requires one inch of water to stay healthy. Place an empty tuna can on your lawn while you water. When the can is full stop watering. (Halton Water Efficiency Program).

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