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What is Source Water?

Source water is untreated water taken from rivers, lakes or underground aquifers to supply private and public drinking water systems.

There are two types of source water:

Surface water is water that lies on the Earth’s surface, in such forms as lakes, rivers and streams. It is drawn into a drinking water system through an intake pipe. Surface water is easily contaminated by pollution flowing over the land or directly into lakes, rivers and streams. Pollution can also come from the air or from materials at the bottom of a body of water.

Groundwater is the water beneath the Earth’s surface, found in the cracks and spaces between soil, sand and rock particles. It is drawn into a drinking water system through a well. Surface water and groundwater can be interconnected, with pollutants finding their way from one to another. Groundwater can also be contaminated by pollutants that are deposited on the surface soil or underground. Groundwater contamination can be much more difficult than surface water pollution to fix.

Protecting source water is the most cost-effective and reliable way to safeguard the quality of our drinking water.

Why Does Ontario Protect Source Water?

Ontario's current commitment to source water protection has its roots in the Walkerton crisis of 2000. The provisions of the Clean Water Act, 2006 reflect the determination to ensure that such a tragedy never happens again.

Visit the Province of Ontario's Source Protection Page

Walkerton and its Aftermath

In May 2000, heavy rains washed E. coli bacteria into a well serving the municipal water system for the small town of Walkerton, Ontario. The resulting contamination left seven people dead and caused more than 2,300 to fall ill.

The subsequent public inquiry, led by Justice Dennis O’Connor of the Supreme Court of Ontario, produced a two-part report with more than 120 recommendations for protecting the safety of the province’s drinking water.

Justice O’Connor concluded that the best way to ensure a healthy water supply is to create mulitple barriers to keep contaminants from reaching people. He identified five parts to such a multi-barrier system:

  1. Source water protection
  2. Adequate treatment
  3. Secure distribution systems
  4. Proper monitoring and testing
  5. Strategic responses to adverse conditions

The first of these barriers, source water protection, would require a very specific approach. Justice O’Connor recommended planning, developing and implementing source protection plans at the local level, for every watershed in Ontario. This recommendation would lead to the introduction of the Clean Water Act, 2006.

The Clean Water Act, 2006

The Clean Water Act, 2006 established a locally-driven, science-based, multi-stakeholder process for safeguarding drinking water sources. Its focus: protecting water before it enters the municipal drinking water system. Under the legislation, local source protection committees across the province are tasked with creating source protection plans for their areas.

The Act represented a significant shift in Ontario’s approach to protecting its water resources. Before Walkerton, provincial policy focused primarily on water’s ecological and recreational value. The Clean Water Act, 2006 puts the goal of public health protection front and centre.

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