What Are Drinking Water Threats?

Human activities can have a direct impact on drinking water sources. Contaminants released on the surface can seep into underlying groundwater aquifers or drain into surface water bodies and compromise the quality of drinking water supplies. 

A drinking water threat is an activity that adversely affects or has the potential to adversely affect the quality or quantity of any water that is or may be used as a source of drinking water. Under the Clean Water Act and its associated regulations, the Province of Ontario has identified 21 drinking water threat activities that can impact drinking water.   

The 21 Prescribed Drinking Water Threats

  1. The establishment, operation or maintenance of a waste disposal site within the meaning of Part V of the Environmental Protection Act.
  2. The establishment, operation or maintenance of a system that collects, stores, transmits, treats or disposes of sewage.
  3. The application of agricultural source material to land.
  4. The storage of agricultural source material.
  5. The management of agricultural source material.
  6. The application of non-agricultural source material to land.
  7. The handling and storage of non-agricultural source material.
  8. The application of commercial fertilizer to land.
  9. The handling and storage of commercial fertilizer.
  10. The application of pesticide to land.
  11. The handling and storage of pesticide.
  12. The application of road salt.
  13. The handling and storage of road salt.
  14. The storage of snow.
  15. The handling and storage of fuel.
  16. The handling and storage of a dense non-aqueous phase liquid.
  17. The handling and storage of an organic solvent.
  18. The management of runoff that contains chemicals used in the de-icing of aircraft.
  19. An activity that takes water from an aquifer or a surface water body without returning the water taken to the same aquifer or surface water body.
  20. An activity that reduces the recharge of an aquifer.
  21. The use of land as livestock grazing or pasturing land, an outdoor confinement area, or a farm animal yard.

Policies in the source protection plan outline how each of these activities will be addressed if they are determined to pose a significant drinking water threat. 

When is A Drinking Water Threat Significant?  

An activity can only be a significant drinking water threat if it is performed in a source protection vulnerable area and meets certain site-specific circumstances, such as the proximity to a municipal well, soil type, and factors such as the type and volume of chemical being handled or stored.  Source Protection Plan policies focus on activities that are significant drinking water threats.  The Town’s Risk Management Official (RMO) and Risk Management Inspector (RMI) will help determine if source protection policies apply to any particular activity.    

Regardless of whether a drinking water threat activity is deemed to be significant or not, it is always a good idea to take extra precautions when conducting activities that pose a hazard to water supplies.  Implementing safety measures and best management practices will ensure risks to water resources are minimized.