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Middlesex-London Health Unit

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Private Well Water

Water that comes from a well and serves a single household is known as private well water.

The Middlesex-London Health Unit suggests that private residences test their well water frequently, as water supply conditions can change allowing harmful bacteria into drinking water. Examples that could change water quality include: flooding or heavy rain fall/snow melt, well condition/maintenance, or nearby construction. Sign up for Well Water Testing Reminder Services for reminders to test your well water or to have water sample bottles mailed to you.


Table of Contents

Why should I test my private well water?

Water quality can change throughout the year. Even if your well water looks fine, it may have harmful bacteria or other contaminants in it that you cannot see, taste, or smell. Drinking contaminated well water can make you and your family members sick and it can even be fatal.

Bacterial contamination may cause stomach cramps, diarrhea, vomiting or other problems. The only way to know if your well water is safe is to have it tested.

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How can I get my private well water tested?

Year round well water testing (for total coliforms and E. coli bacteria) for private residences (homes) is provided for free by the London Public Health Laboratory. Water samples must be collected in water bottles provided by a public health laboratory, and in a certain way, in order to be accepted for testing.

See water bottle pick-up and drop-off locations to find out where in Middlesex-London you can get a proper water testing kit (water bottle and form).

To make sure your well water sample can be tested, follow the steps given on Public Health Ontario’s Well Water Testing web page. Be sure to collect your water sample in this way so that you will get a true result for your well water quality. You can also view the Grey Bruce Public Health Unit's video on how to take a drinking water sample and submit it to your local Public Health Ontario laboratory.

*Note: Total coliforms and E. coli bacteria testing are free. If a homeowner is looking for chemical or other water tests they can submit samples to a licensed drinking water testing lab and pay for this service. A water sample that has 0 total coliforms and 0 E. coli may still be positive for other microorganisms, chemicals and radiological contamination.

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How do I get my well water test results?

Please see Public Health Ontario’s Well Water Testing: Get and Understand Your Results for more information on how to obtain your well water test results.

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What do my well water test results mean?

To learn about total coliforms and E. coli bacteria, and what the counts for each in your well water test results mean, visit Public Health Ontario’s Well Water Testing: Get and Understand Your Results web page.

If you have test results that say your water is unsafe to drink, or you need help figuring out what your well water test results mean, speak to a Public Health Inspector on the Environmental Health Team at:

  • 519-663-5317

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Private Well Water Manual

A picture of the front cover of the Private Well Water Manual

View, download and print →


Private Wells

A picture of a private well


A picture of a drilled well

Additional Information

A Private Well Water Manual (A quick users guide) (PDF 4.5 MB) has been developed by the Middlesex-London Health Unit. It contains information about wells, groundwater, well construction, well maintenance, chlorination, monitoring, testing and other well water topics. To request a paper copy of this resource, please call:

  • 519 663 5317

View Well Records to see how to complete, submit or get a copy of a well record in Ontario. You may also be able to search and view well record information from reported wells in Ontario through the Map: Well records catalogue.

To speak to a Public Health Inspector on the Environmental Health Team about well water, collecting water samples, or well water test results, please call:

  • 519-663-5317
Date of creation: December 12, 2012
Last modified on: January 24, 2022