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Flooded Private Water Supply

Testing Your Water After Your Well has Flooded

​​​​​​​​​​​​​Heavy rain and flooding can cause surface water to enter your private water well. This means there is a risk of harmful germs (bacteria) getting in and contaminating the water. Test your well water for bacteria after flood waters go down (recede) to make sure it’s safe.

Don’t drink untreated well water until you get your test results back. You may need to boil your water while you’re waiting for your results.

How do I make sure my well water is safe after heavy rain or flooding?

The Provincial Laboratory for Public Health (ProvLab) tests private drinking water systems. However, the ProvLab can’t test water for every type of harmful germ. The ProvLab does 2 standard tests on water samples to show how likely they are to be contaminated with bacteria.

The ProvLab tests for:

  • total coliforms - a group of bacteria found everywhere (e.g., in soil, on plants, in lake and river water)
  • E. coli - bacteria that people and some types of animals have in their bowels and stools. If you have E. coli in your drinking water, it’s not sa​fe. Your water has been contaminated by human or animal waste.

When do I need to test my water?

After the heavy rain stops and the flooding is over, send a water sample to a lab for testing.

If your first water sample results shows:

  • bacteria are absent - send another sample 14 to 30 days later to make sure the water is still safe
  • bacteria are present - a public health inspector will call you. You may be told to shock chlorinate your well.

For More Information

Find out more about water safety including:

  • how to collect a water sample for testing
  • where to pick up and drop off water sample bottles
  • understanding your water sample test results

Current as of: March 7, 2018

Author: Environmental Public Health, Alberta Health Services