TORONTO - Most Canadians are blissfully unaware that the water they take for granted is being threatened by overuse and mismanagement, say experts who warn climate change could soon make water shortages an unmistakable reality across the country.

The United Nations is using Saturday's World Water Day to warn about the impending dangers of water scarcity -- shortages that could affect two-thirds of the world's population by 2025.

Canadian advocates say they hope the day will also raise awareness about this country's pressing water issues and dispel the myth that we're immune to the shortages emerging around world.

"We've become very complacent about the richness that we have and it's kind of caught up to us in many ways, or is catching up to us,'' said Rick Findlay, the water program director at Pollution Probe, which released a report on Thursday about the need for better water management.

"It's not that we have a disaster situation on our hands, but we definitely need to take a new approach to the way that we manage water to make sure we have the needs of the future looked after.''

Canada may be home to some of the world's largest lakes and rivers but it's a common misconception the country has an endless supply of water that could never be drained, said Bob Sanford, chairman of Canada's branch of the United Nations' Water for Life program.

Only a tiny percentage of Canada's water is naturally replenished each year and every region of the country is facing very real threats to its water supply, according to a recently-released report on climate change produced for Natural Resources Canada.

Water shortages have already been documented in southern Ontario as the region's population has rapidly grown and they're expected to become more frequent as summer temperatures and evaporation rates increase, according to the report, entitled: From Impacts to Adaptation: Canada in a Changing Climate.

The report concludes that scarcity is also expected to worsen in the Prairies and will pose the most serious water risk in the country.

Glacial retreat and increasing demands on water from residential and commercial users -- particularly the booming agriculture and oilsands industries -- could limit the region's social and economic development and cause serious environmental issues.

"Our assessment is (water shortages at home) shouldn't surprise Canadians, given our population is growing and our demands on water resources in industry, agriculture and other uses,'' Sanford said.

"Some of the problems that are occurring elsewhere in the world should start to happen here and that's exactly what's happening.''

Water management is currently left to the jurisdiction of provinces and Canada lacks a good understanding of exactly what's happening from coast to coast, both good and bad, said University of Guelph Prof. Rob De Loe, who also wrote a report on the state of water management across Canada.

"It's very common to hear of neglect -- benign or otherwise -- of our rules and systems for allocating water resources and there's lots of stories from across the country,'' he said.

Climate change is being recognized as a serious factor that could affect water supplies but few jurisdictions have begun to change their policies to reflect those concerns and continue to deal with their water based on historical guidelines, De Loe said.

"Are we dealing with this? Do we understand the impacts and what the impacts are going to be? Do the systems allow us to manage these in a proactive way? The answer is mostly no.''

Sanford said it might take a disastrous wake-up call before individuals, industries and governments realize there's too much water being wasted in Canada. He warned it won't necessarily be very long before something serious happens.

"We take water for granted and because we believe we have so much of it, we waste it, and we don't understand that our uses are becoming manifold and quite heavy,'' he said.

"We have lived with this myth for a very long time and because we often operate in isolated jurisdictions we may not understand the stress we're putting on our own water.''